AArch64 always omit leaf frame pointer

Hi Devs,

By default AArch64 omit the frame pointer for leaf function.
But surprisingly, even after passing option -mno-omit-leaf-frame-pointer behavior remain same.

it is handled at
https://github.com/llvm-mirror/llvm/blob/master/lib/Target/AArch64/AArch64FrameLowering.cpp#L242

Here is a testcase
https://godbolt.org/z/653p3q

Before going for fix,
Like to know community thought on this wether this is a bug or not?

./Kamlesh

X86 and Mips respect -mno-omit-leaf-frame-pointer. gcc aarch64
defaults to -mno-omit-leaf-frame-pointer. So it seems we should
probably fix AArch64. PowerPC has a similar problem.

We need a clang driver patch to make AArch64 similar to PS4, which
defaults to -mno-omit-leaf-frame-pointer:
https://reviews.llvm.org/D71167