bug#21777: 25.0.50; gud-gdb uses a pager, which is harmful inside emacs

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: dima@secretsauce.net,  21777@debbugs.gnu.org,  schwab@linux-m68k.org
> Date: Thu, 24 Sep 2020 16:29:06 +0200
> 
> And I'm guessing that the pager doesn't get switched on in the M-x gdb
> case because the communication is over a separate socket (-i=mi), and
> gdb just ignores the notification in that case?

In the -i=mi case, GDB doesn't behave as if its output is a terminal
device.