macros/726: Internal GDB errors with current GDB snapshots and -gdwarf2-3

[Jim Blandy]

This points out an interesting issue.  I can attach a patch to a PR in
two ways, neither of which are really satisfactory:

- I can attach the patch directly to the PR, which causes GNATS to
  generate E-mail messages that refer to "attachments" that are not
  present in the message.

- Or, if I'm replying to a PRMS message, I can attach the patch to the
  message, which results in the patch not appearing as an attachment
  to the PR itself.

Hmph.  I could always just do both, I suppose.