Add spec for not seeking when no offset is given

Extracted from #2755
Don't call IO#pos if no offset is given

Fixes #2755
Add spec for String#match calling Regexp#match
Ensure that String#match calls Regexp#match

Fixes #2763
Removed stdlib stubs.
Fixed handling C++ exception unwinding through NativeMethod call.

The issue here was exposed by the following RubyGems code:

  Zlib::GzipReader.wrap(*args) do |gzio|
    @spec = Gem::Specification.from_yaml gzio.read
  end

GzipReader.wrap is a NativeMethod (Ruby method implemented by a C function)
that yields to a block. Gem::Specification.from_yaml is another NativeMethod.
When it ran, a Ruby exception at the VM level was thrown and the stack was
unwound through the NativeMethod::executor_implementation for
Gem::Specification.from_yaml. This didn't allow the NativeMethod executor to
clean up the stack. The rb_yield implementation received a NULL value from the
Ruby block code, indicating an exception had occurred, causing the rb_yield
implementation to access invalid data while trying to handle the exception (ie
execute a longjmp to the exception handling code above it).

The code duplication here is annoying but the lifetime of the exception
objects is difficult. We should probably handle native method
frame setup and teardown (and the enter/leave C-API code) in a scoped object
the way we handle the profiler and other locks.
Adjusted some gem requirements.
Added method for loading files required by rubygems.
Fixed finding some bootstrap code.
Removed extra check for bootstrap libraries.

There will always be rubygems in the stack trace because rubygems is
always loaded by default.

This craptastic hack will hopefully be made obsolete by a better hook in
rubygems when loading standard libraries.
Fixed bundle --path.
Updated RubyGems to 2.1.10.

=== 2.1.9 / 2013-10-14

Bug fixes:

* Reduce sorting when fetching specifications.  This speeds up the update and
  outdated commands, and others.  Issue #657 by windwiny.
* Proxy usernames and passwords are now escaped properly.  Ruby Bug #8979 by
  Masahiro Tomita, Issue #668 by Kouhei Sutou.

=== 2.1.8 / 2013-10-10

Bug fixes:

* Fixed local installation of platform gem files.  Issue #664 by Ryan Melton.
* Files starting with "." in the root directory are installed again.  Issue
  #680 by Ivo Wever, Pull Request #681 by Jeremy Evans.
* The index generator no longer indexes default gems.  Issue #661 by
  Jeremy Hinegardner.

=== 2.1.7 / 2013-10-09

Bug fixes:

* `gem sources --list` now displays a list of sources.  Pull request #672 by
  Nathan Marley.
* RubyGems no longer alters Gem::Specification.dirs when installing.  Pull
  Request #670 by Vít Ondruch
* Use RFC 2616-compatible time in HTTP headers.  Pull request #655 by Larry
  Marburger.
* RubyGems now gives a more descriptive message for missing licenses on
  validation.  Issue #656 by Markus Heiler.
* Expand unpack destination directory.  This fixes problems when File.realpath
  is missing and $GEM_HOME contains "..".  Issue #679 by Charles Nutter.

=== 2.1.6 / 2013-10-08

Bug fixes:

* Added certificates to follow the s3.amazonaws.com certificate change.  Fixes
  #665 by emeyekayee.  Fixes #671 by jonforums.
* Remove redundant built-in certificates not needed for https://rubygems.org
  Fixes #654 by Vít Ondruch.
* Added test for missing certificates for https://s3.amazonaws.com or
  https://rubygems.org.  Pull request #673 by Hannes Georg.
* RubyGems now allows a Pathname for Kernel#require like the built-in
  Kernel#require.  Pull request #663 by Aaron Patterson.
* Required rbconfig in Gem::ConfigFile for Ruby 1.9.1 compatibility.  (Ruby
  1.9.1 is no longer receiving security fixes, so please update to a newer
  version.)  Issue #676 by Michal Papis.  Issue wayneeseguin/rvm#2262 by
  Thomas Sänger.

=== 2.1.5 / 2013-09-24

Security fixes:

* RubyGems 2.1.4 and earlier are vulnerable to excessive CPU usage due to a
  backtracking in Gem::Version validation.  See CVE-2013-4363 for full details
  including vulnerable APIs.  Fixed versions include 2.1.5, 2.0.10, 1.8.27 and
  1.8.23.2 (for Ruby 1.9.3).

=== 2.1.4 / 2013-09-17

Bug fixes:

* `gem uninstall foo --all` now force-uninstalls all versions of foo.  Issue
  #650 by Kyle (remkade).
* Fixed uninstalling gems installed in the home directory (as in
  `--user-install`).  Issue #653 by Lin Jen-Shin.

=== 2.1.3 / 2013-09-12

Bug fixes:

* Gems with files entries starting with "./" no longer install 0 files.  Issue
  #644 by Darragh Curran, #645 by Brandon Turner, #646 by Alex Tambellini

=== 2.1.2 / 2013-09-11

Bug fixes:

* Restore concurrent requires following the fix for ruby bug #8374.  Pull
  request #637 and issue #640 by Charles Nutter.
* Gems with extensions are now installed correctly when the --install-dir
  option is used.  Issue #642 by Lin Jen-Shin.
* Gem fetch now fetches the newest (not oldest) gem when --version is given.
  Issue #643 by Brian Shirai.

=== 2.1.1 / 2013-09-10

Bug fixes:

* Only matching gems matching your local platform are considered for
  installation.  Issue #638 by José M. Prieto, issue #639 by sawanoboly.

=== 2.1.0 / 2013-09-09

Security fixes:

* RubyGems 2.0.7 and earlier are vulnerable to excessive CPU usage due to a
  backtracking in Gem::Version validation.  See CVE-2013-4287 for full details
  including vulnerable APIs.  Fixed versions include 2.0.8, 1.8.26 and
  1.8.23.1 (for Ruby 1.9.3).  Issue #626 by Damir Sharipov.

Major enhancements:

* RubyGems uses a new dependency resolver for gem installation which works
  similar to the bundler resolver.  The new resolver can resolve conflicts the
  previous resolver could not and offers improved diagnostics when conflicts
  are discovered.

Minor enhancements:

* RubyGems now has improved platform matching for the ARM architecture.  Gems
  built with a CPU of "arm" will match any specific ARM CPU.  See `gem help
  platform` for further details.  Fixes #532 by Kim Burgestrand.
* The --version option now accepts compound requirements the same as in a gem
  dependency.  The following invocation will install rails between 4.0.0.beta
  and 4.2:

    gem install rails -v '>= 4.0.0.beta, < 4.2'

  Fixes #531 by Gary S. Weaver
* `gem clean` now allows `-n` as an alias for `--dryrun`.  Pull Request #517
  by Gastón Ramos
* Added `gem update --system` to `gem help`.  Pull Request #514 by Vince
  Wadhwani
* Added PATH to `gem env` output.  Pull Request #490 by Michal Papis
* Added --host option to `gem owner` to match other commands using the
  gemcutter API.  Pull Request #462 and issue #461 by Hugo Lopes Tavares
* Added --abort-on-dependent to `gem uninstall`.  This will abort instead of
  asking to uninstall a gem that is depended upon by another gem.  Pull
  request #549 by Philip Arndt.
* RubyGems no longer alters Gem::Specification.dirs when installing.  Based on
  Pull Request #452 by Vít Ondruch
* RubyGems uses ENV['MAKE'] or ENV['make'] over rbconfig.rb's make if present.
  Pull Request #443 by Erik Hollensbe
* RubyGems can now save remote source cache files in an alternate directory
  controlled by `ENV["GEM_SPEC_CACHE"]`.  Pull Request #489 by Michal Papis
* Generated private keys are now encrypted.  Pull Request #453 by pietro
* Separated Gem::Request from Gem::RemoteFetcher.  Pull Request #283 by Steve
  Klabnik.
* RubyGems indicates when a .gem's content is corrupt while verifying.  Bug
  #519 by William T Nelson.
* Refactored common installer setup.  Pull request #520 by Gastón Ramos
* Moved activation tests to Gem::Specification.  Pull request #521 by Gastón
  Ramos
* When a --version option with a prerelease version is given RubyGems
  automatically enables prerelease versions but only the last version is
  used.  If the first version is a prerelease version this is no longer sticky
  unless an explicit --[no-]prerelease was also given.  Fixes part of #531.
* RubyGems now supports an SSL client certificate.  Pull request #550 by
  Robert Kenny.
* RubyGems now suggests how to fix permission errors.  Pull request #553 by
  Odin Dutton.
* Added support for installing a gem as default gems for alternate ruby
  implementations.  Pull request #566 by Charles Nutter.
* Improved performance of Gem::Specification#load by caching the loaded
  gemspec.  Pull request #569 by Charlie Somerville.
* RubyGems now warns when an unsigned gem is verified if -P was given during
  installation even if the security policy allows unsigned gems and warns when
  an untrusted certificate is seen even if the security policy allows
  untrusted certificates.  Issue #474 by Grant Olson
* RubyGems can now rewrite executables with or without a shebang of
  /usr/bin/env via <code>gem pristine --all --only-executables
  --env-[no-]shebang</code>.  Issue #579 by Paul Annesley.
* RubyGems can now run its tests without OpenSSL.  Ruby Bug #8557 by nobu.
* Improved performance by caching Gem::Version objects and avoiding
  method_missing in Gem::Specification.  Pull request #447 by Jon Leighton.
* Files in a .gem now preserve their modification times.  Pull request #582 by
  Jesse Bowes
* Improved speed of looking up dependencies in SpecFetcher through
  Array#bsearch (when present).  Pull request #595 by Andras Suller
* Added `--all` option to `gem uninstall` which removes all gems in GEM_HOME.
  Pull request #584 by Shannon Skipper.
* Added Gem.find_latest_files which is equivalent to Gem.find_files but only
  returns matching files from the latest version of each gem.  Issue #186 by
  Ryan Davis.
* Improved performance of `gem outdated` by reducing duplicate work (it is
  still slow, but I see a near 50% improvement for 250 gems on a fast
  connection).  See also Gem::Specification::outdated_and_latest_version

Bug fixes:

* rubygems_plugin.rb files are now only loaded from the latest installed gem.
* Fixed Gem.clear_paths when Security is defined at top-level.  Pull request
  #625 by elarkin
* Fixed credential creation for `gem push` when `--host` is not given.  Pull
  request #622 by Arthur Nogueira Neves

------------------------------------------------------------------------------

RubyGems installed the following executables:
  /source/rubinius/rubinius/bin/gem

RubyGems system software updated
Fix spec to actually use maximum uint value
Fix range check for rb_fix2uint

Fixes #2770
Add specs for rb_ary_subseq
Add implementation for rb_ary_subseq

Fixes #2769
Fix install error of rubygems without stdlib
Merge pull request #2773 from ryoqun/rubygems-without-stdlib

Fix install error of rubygems without stdlib
Bump configure version because of added Rubygems dependencies
Add spec on Process.spawn with non-existing command.