More bugs page updates

[Andrew Cagney]

Hello,

I've updated http://sources.redhat.com/gdb/bugs/ to include two 
paragraphs (lifted mostly from www.gnu.org).

- 
a paragraph to steer the submitter towards distributors when submitting 
bugs for distributor versions of GDB

- 
a paragraph to let people know that we don't promise to fix bugs.  It 
steers people towards the FSF support list.

Some people may have reservations about these.  So please comment! :-)

Andrew