Added ruby_conf_opts to ruby::version
Added cflags param to ruby::version
Added ruby 1.9.3-p392 with performance patches
Updated cflags in ruby::version

Building ruby fails due to recent changes by Apple to clang. Setting
the -Wno-error=shorten-64-to-32 option solves the problem. See
https://bugs.ruby-lang.org/issues/7946#change-36951 for a more in depth
explanation.