(Gem::Ext::Builder.run): EXIT_SUCCESS may be 0 or may not.
* test/rubygems/test_gem_ext_rake_builder.rb (build_rake_in): override
Gem.ruby and ENV["rake"].
* runruby.rb: bin/rake does not exist in archdir where architecture
depend script (i.e. rbconfig.rb) exists.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@17758 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
nobu
drbrain