gdb: remove -Werror annotations from MAINTAINERS file

I don't think these are useful nowadays, since we now expect all code to
be -Werror clean (it's the default in development branches).

Change-Id: I8c3b86c70d683bd41344d27add0ac2627a474d20
Approved-By: Tom Tromey <tom@tromey.com>
1 file changed