[test] Improve inline asm 'p' constraint tests (#185681)
Move clang/test/CodeGen/inline-asm-p-constraint.c to
clang/test/CodeGen/AArch64/ since inline asm constraint support is
target-dependent (clang/lib/Basic/Targets/AArch64.h modified by
https://reviews.llvm.org/D76297)
Add `test_a_p` to clang/test/CodeGen/X86/inline-asm-constraints.c to
test the 'a' modifier with 'p' constraint for both pointer and integer
operands. Extracted from #185590
