Add patch to make ocamlopt -output-obj and ocamlopt -pack call the linker

Add patch to make ocamlopt -output-obj and ocamlopt -pack call the linker
via gcc instead of directly, which allows us to pass the same linking
options in these cases and in the common case (where ocamlopt already used
gcc). This should unbreak ocamlopt -pack on alpha, and thus fix the build
failure of camomile.