ruby: add missing dependency on gmp
ruby: add missing dependency on gmp

It was pulled in indirectly via gcc, but not in clang envs.
Make it explicit

JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,lhmouse/MINGW-packages,oroppas/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,oroppas/MINGW-packages,oscarfv/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,oscarfv/MINGW-packages,oroppas/MINGW-packages,oroppas/MINGW-packages,lhmouse/MINGW-packages,oscarfv/MINGW-packages,oroppas/MINGW-packages,oroppas/MINGW-packages,stahta01/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages