This patch enables passing non variadic vector type parameters on the caller and callee side and vector return on AIX that are passed in vector registers only.
So far, support is enabled for only the AIX extended Altivec ABI Calling convention.
Reviewed By: sfertile, DiggerLin
Differential Revision: https://reviews.llvm.org/D86476
Added support for the options mabi=vec-extabi and mabi=vec-default which are analogous to qvecnvol and qnovecnvol when using XL on AIX.
The extended Altivec ABI on AIX is enabled using mabi=vec-extabi in clang and vec-extabi in llc.
Reviewed By: Xiangling_L, DiggerLin
Differential Revision: https://reviews.llvm.org/D89684