import 1.9.3-p551 definition
install addtional definition from upstream
import patches under lang/ruby19/files
disable rdoc and use macro for CC
support 1.9.x

- use more macros (MY_RUBY_VER)
- use gcc 4.6 for 1.8.x build
- add libtool to USES
- use find(1) to strip shared libs instead of file glob
add ruby 1.9.3p551