1.9.2-p180 needs non-llvm gcc (ref rbenv#137)

Author: sstephenson

share/ruby-build/1.9.2-p180

@@ -1,3 +1,4 @@
+require_gcc
 install_package "yaml-0.1.4" "http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz"
 install_package "ruby-1.9.2-p180" "http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.2-p180.tar.gz"
 install_package "rubygems-1.8.23" "http://production.cf.rubygems.org/rubygems/rubygems-1.8.23.tgz" ruby