[maint] The GDB maintenance process

[Mark Kettenis]

I mostly agree with Daniel here.  We have too many single points of
failure.  I still have testsuite patches sitting in my tree, dating
months back since they were never approved.  Similarly, Daniel
probably has been held back more than once since I wasn't able to
review threads-related patches in a timely fashion.  I think we should
allow our global maintainers to approve patches even for parts of GDB
where we have a specific maintainer, if they feel they have the
necessary expertise.

Mark