[flang][driver] Ensure negative flags have the same visibility as positive

https://reviews.llvm.org/D157151 and https://reviews.llvm.org/D157837
added visibility flags to flang options, hiding options which are
supported only in Clang and not in Flang.

After this change, some negative flags e.g. `-fno-reciprocal-math` no
longer work with flang. These flags are supported in flang (as can be
seen from the support for the positive flags).

I also opted to make sure the clang visibility is the same on these
flags, although I did not look at changing the visibility of non-flang
flags.

Differential Revision: https://reviews.llvm.org/D158612