Support BTI & PAC properties in aarch64 GNU note details

[fanquake]

It'd be nice if this was supported (i.e in the details output) similar to the Linux ABI/Version.

For example, a binary compiled with -mbranch-protection=standard (can also be just =bti):

int main() {
	return 0;
}

# readelf -n a.out

Displaying notes found in: .note.gnu.property
  Owner                Data size 	Description
  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
      Properties: AArch64 feature: BTI, PAC

[romainthomas]

In progress