Avoid crash with "NSString" literals

Evaluating an Objective-C "NSString" literal will cause gdb to crash.
This patch fixes the crash.

I think the result here still isn't correct -- I see a warning from
the runtime ("autorelease called without pool for object") with the
new code.

However, not crashing is an improvement on its own.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=20501



3 files changed