Don't add $LOAD_PATH for default gem

It is needless because load path for default gems are included in
$LOAD_PATH by default.
"We all know syck has been removed" -- nobu

Imported r38100 from ruby trunk
Fix a bug that 'gem cleanup' can't uninstall the second or later gems

Gem.use_paths requires GEM_HOME as the first argument but
CleanupCommand doesn't passes it as the first argument. So the second
or later gems can't use the restored GEM_HOME.

TODO: We need to write a test but I don't have a time for now. Sorry. :<

See also: https://bugs.ruby-lang.org/issues/7481

Here is a command list to reproduce this problem:

Install two gems:

  % /tmp/local/bin/gem install mongo psych
  ...
  Installing ri documentation for mongo-1.8.0
  ...
  Installing ri documentation for psych-1.3.4
  ...

Install old gems:

  % /tmp/local/bin/gem install mongo -v 1.7.1
  ...
  Successfully installed mongo-1.7.1
  ...

(psych is already installed as default gem. So we doesn't need to
install old psych gem explicitly.)

Run cleanup that uinstalls two gems (psycn and mongo) and the later
gem (mongo) can't be uninstalled:

  % /tmp/local/bin/gem cleanup
  Cleaning up installed gems...
  Attempting to uninstall psych-1.3.4
  Successfully uninstalled psych-1.3.4
  Attempting to uninstall mongo-1.7.1
  Unable to uninstall mongo-1.7.1:
          Gem::InstallError: mongo is not installed in GEM_HOME, try:
          gem uninstall -i /tmp/local/lib/ruby/gems/2.0.0 mongo
  Clean Up Complete
Added Source to the autoload list and sorted it
Test for 24fdcd74

Ensured gem cleanup does not alter Gem.dir or Gem.path.  This lead to
odd messages about needing to use special commands to uninstall from
your GEM_HOME directory.
Omit the zulu timestamp test except for 1.9.2.

Imported r38125 from rubytrunk.
Fixed Gem::Specification#validate_permissions for ruby 1.8
Fixed Gem.detect_gemdeps for $SAFE=1
Added notes about this release to History.txt
Ignore default gems in cleanup

rubygems/rubygems#408
Set rubygems_version before package validation

This fixes an issue in bundler with 2.0.0.preview2
Only update the cache when we have permission

In RubyGems 1.8 we would only update the cache directory when we had the
correct permissions.  During the refactorings in master this check was
lost.  Now cache_update_path can update the spec cache only when it has
the correct permissions.

Fixes ruby bug #7509
Fixed Gem::Specification#base_dir for default gems

Default gem specs are loaded one level deeper than regular specs so
Gem::Specification#base_dir must remove one extra directory.

Fixes ruby bug #7469
Stop syncing gauntlet_rubygems.rb
Removed "useless" string concatenation syntax
Allowing :build_args to be passed to Gem::DependencyInstaller.new, which will then pass them on to Gem::Installer.new
Adding test for Gem::DependencyInstaller.new accepting :build_args.

The test is modelled after the first, simplest test in this file,
and reads the generated info file.
Regenerated test certificates for FIPS mode

Previously the test certificates had (broken) 512 bit keys which are too
short for FIPS mode.  The new keys have 2048 bit keys which should last
a good while.  Fixes #365

Updated History.txt for commits since 2.0.0.preview2
Merge pull request #412 from srawlins/master

Allow DependencyInstaller.new to receive :build_args
Merge pull request #409 from kou/ignore-default-gems-in-cleanup

Ignore default gems in cleanup