[updated, following some comments from Gerald, main differences are
  slight tweaks to the html markup and changing "email" to "e-mail"]

This patch proposes some new (additional) rules for email subject lines
when contributing to GCC.  The goal is to make sure that, as far as
possible, the subject for a patch will form a good summary when the
message is committed to the repository if applied with 'git am'.  Where
possible, I've tried to align these rules with those already in
use for glibc, so that the differences are minimal and only where
necessary.

Some things that differ from existing practice (at least by some people)
are:

- Use '<topic>:' rather than '[<topic>]'
   - This is more git friendly and works with 'git am'.
- Put bug numbers at the end of the line rather than the beginning.
   - The bug number is useful, but not as useful as the brief summary.
     Also, use the shortened form, as the topic part is more usefully
     conveyed in the proper topic field (see above).