Add additional cases for String#to_i benchmarks
Add spec for turning string into Bignum for String#to_i
Improve performance of String#to_i for Fixnum sized numbers

This improves performance by using a native_int directly instead of
going through Fixnum::mul for small numbers.

Before:

=== bin/rbx ===
                     23003211.6 (±2.9%) i/s -  114623120 in   4.987875s
                      8712371.5 (±3.0%) i/s -   43457940 in   4.993010s
                     22075592.9 (±3.5%) i/s -  110172960 in   4.998188s
                      9270667.3 (±1.7%) i/s -   46350018 in   5.001216s
                     26227093.3 (±2.4%) i/s -  130860198 in   4.992595s
                     21890007.0 (±2.0%) i/s -  109247625 in   4.992789s
                      2778600.2 (±5.4%) i/s -   13821408 in   4.996930s

After:

=== bin/rbx ===
                     26079388.8 (±2.5%) i/s -  129962508 in   4.986793s
                     14049298.6 (±2.4%) i/s -   70156344 in   4.996964s
                     24275838.8 (±4.2%) i/s -  120887196 in   4.991455s
                     13268209.3 (±3.4%) i/s -   66240912 in   4.999549s
                     28462400.4 (±2.1%) i/s -  141973920 in   4.990660s
                     24266645.9 (±3.2%) i/s -  120924700 in   4.988763s
                     12897795.2 (±2.1%) i/s -   64409609 in   4.996203s
Also expose *_gvl functions in 1.9 mode

Apparently this also works with MRI 1.9.

Fixes #2566
Removed stdlib English spec from language specs.
Removed require for stdlib enumerator in core specs.
Removed profiler and coverage extensions.
Added profiler and coverage gems to configure.
Fixed loading profiler for custom mspec guard.
Removed building FFI standard libs.
Add additional cases for String#to_i benchmarks
Add spec for turning string into Bignum for String#to_i
Improve performance of String#to_i for Fixnum sized numbers

This improves performance by using a native_int directly instead of
going through Fixnum::mul for small numbers.

Before:

=== bin/rbx ===
                     23003211.6 (±2.9%) i/s -  114623120 in   4.987875s
                      8712371.5 (±3.0%) i/s -   43457940 in   4.993010s
                     22075592.9 (±3.5%) i/s -  110172960 in   4.998188s
                      9270667.3 (±1.7%) i/s -   46350018 in   5.001216s
                     26227093.3 (±2.4%) i/s -  130860198 in   4.992595s
                     21890007.0 (±2.0%) i/s -  109247625 in   4.992789s
                      2778600.2 (±5.4%) i/s -   13821408 in   4.996930s

After:

=== bin/rbx ===
                     26079388.8 (±2.5%) i/s -  129962508 in   4.986793s
                     14049298.6 (±2.4%) i/s -   70156344 in   4.996964s
                     24275838.8 (±4.2%) i/s -  120887196 in   4.991455s
                     13268209.3 (±3.4%) i/s -   66240912 in   4.999549s
                     28462400.4 (±2.1%) i/s -  141973920 in   4.990660s
                     24266645.9 (±3.2%) i/s -  120924700 in   4.988763s
                     12897795.2 (±2.1%) i/s -   64409609 in   4.996203s
Removed standard lib etc.
Added check + create for runtime/gems directory.
Added rubysl-etc to gems needed to build C-exts.
Fixed building bootstrap gems.
Cleaned up more left over stdlib.
Merge remote-tracking branch 'origin/master' into compiler

Conflicts:
	vm/capi/19/include/ruby/ruby.h