In f9f3316, Adrian fixed an issue where LLDB wouldn't update the
target's architecture when the process reported a different triple that
only differed in its sub-architecture.
This unintentionally regressed core file debugging when the core file
reports the base architecture (e.g. armv7) while the main binary knows
the correct CPU subtype (e.g. armv7em). After the aforementioned change,
we update the target architecture from armv7em to armv7. Fix the issue
by trusting the target architecture over the ProcessMachCore process.
rdar://133834304
9f418057dc