[SPARC][clang] Add SPARC target feature flags

This adds some SPARC feature flags to clang, for those that we have in common with GCC:

-m[no-]fpu
-m[no-]fsmuld
-m[no-]popc
-m[no-]vis
-m[no-]vis2
-m[no-]vis3
-m[hard/soft]-quad-float

All have the same meanings as GCC's options (https://gcc.gnu.org/onlinedocs/gcc/SPARC-Options.html).

This fixes, among other things, the -mno-fpu part of bug #40792

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D139768