bug#8038: report-emacs-bug to be more careful about From: address

[Glenn Morris]

Package: emacs
Severity: minor

Bug reports should have valid From: addresses, so that the submitters
can be contacted for more details, etc.

M-x report-emacs-bug should try to make sure this happens.

i) Put something in the bug help buffer about "remember to check the
>From address is set correctly".

ii) When sending the message, check if the From address looks bogus.
For example, using message-bogus-recipient-p on the From header.
Possibly also checking for a From address that ==
(concat (user-login-name) "@" (system-name))  (the fallback init value),
because I imagine for today's systems that is wrong more often than it
is right.