ruby overwrites configuration files in ruby-native

ruby's install rule is calling install-cross, this overwrites files installed
by ruby-native causing build failures with ruby apps, specifically where gems
are involved, especially on hosts where there is no host ruby:

(from sysroot-native's gem)
gem env
 RubyGems Environment:
   - RUBYGEMS VERSION: 1.8.23
   - RUBY VERSION: 1.9.3 (2012-04-20 patchlevel 194) [x86_64-linux]
   - INSTALLATION DIRECTORY: /usr/lib64/ruby/gems/1.9.1
   - RUBY EXECUTABLE: /usr/bin/ruby
   - EXECUTABLE DIRECTORY: /usr/bin
   - RUBYGEMS PLATFORMS:
     - ruby
     - x86_64-linux
   - GEM PATHS:
      - /usr/lib64/ruby/gems/1.9.1
      - /folk/afong/.gem/ruby/1.9.1
   - GEM CONFIGURATION:
      - :update_sources => true
      - :verbose => true
      - :benchmark => false
      - :backtrace => false
      - :bulk_threshold => 1000
   - REMOTE SOURCES:
      - http://rubygems.org/



Files affected - fake.rb, rbconfig.rb, config.h, win32.h and ruby libraries.
We should be using the versions from ruby-native.

Signed-off-by: Amy Fong <amy.fong@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>