This patch builds on D100521 and other related patches to add support
for unwinding stack on AArch64 systems with pointer authentication
We override FixCodeAddress and FixDataAddress function in ABISysV_arm64
class. We now try to calculate and set code and data masks after reading
data_mask and code_mask registers exposed by AArch64 targets running Linux.
This patch utilizes core file linux-aarch64-pac.core for testing that
LLDB can successfully unwind stack frames in the presence of signed
return address after masking off ignored bits.
This patch also includes a AArch64 Linux native test case to demonstrate
successful back trace calculation in presence of pointer authentication