Add fiddle back in to ruby

mostly this is to add the fiddle extension back in which I need for ffi-yajl related stuff.

this got taken out because 2 years ago we didn't have libffi as a dependency to use i think.

added libffi as a dep because we need it now to link fiddle against.

the refactoring of the flags is also both cleanup and necessary to fix a health-check issue on solaris.