bug#30807: Tramp tests take waaayyy too long and refuse to exit

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Date: Fri, 16 Mar 2018 17:41:16 +0100
> Cc: 30807@debbugs.gnu.org
> 
> > Also, why not make the TEST_PRINT_TEST_DURATION=1 the default? It's a
> > minor hassle to remember to type "make TEST_PRINT_TEST_DURATION=1".
> 
> I have no opinion on this. Glenn? Eli?

If tests becoming slow is something that happens a lot, and we want to
keep track of that, then indeed it sounds like a good idea.
Otherwise, it's just useless clutter.

Alternatively, maybe we should do this only for certain parts of the
suite, where this issue pops frequently.