[AArch64] Enable emission of stack maps for non-Mach-O binaries on AArch64.
The emission of stack maps in AArch64 binaries has been disabled for all
binary formats except Mach-O since rL206610, probably mistakenly, as far
as I can tell. This patch reverts this to its intended state.
Differential Revision: https://reviews.llvm.org/D70069
Patch by Loic Ottet.