get_maintainer: look for arbitrary letter prefixes in sections

get_maintainer: look for arbitrary letter prefixes in sections

Jani Nikula proposes patches to add a few new letter prefixes for "B:"
bug reporting and "C:" maintainer chatting to the various sections of
MAINTAINERS.

Add a generic mechanism to get_maintainer.pl to find sections that have
any combination of "[A-Z]" letter prefix types in a section.

Link: http://lkml.kernel.org/r/1477332323.1984.8.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>