[llvm-symbolizer][llvm-nm] Fix AArch64 and ARM mapping symbols handling.

Exclude AArch64 mapping symbols ($x and $d) for symtab symbolization as
it was done for ARM since D95916 tom bring bots back to green state.

This is implemented by setting SF_FormatSpecific such that
llvm-symbolizer will ignore them, and use this flag to re-implement
llvm-nm --special-syms option which make it work for both targets.

Differential Revision: https://reviews.llvm.org/D98803