[RFC 3/6] mingw-hdep: Add "maint set testuite-mode on/off" command.

[Eli Zaretskii]

> From: "Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>
> Date: Thu, 26 Sep 2013 22:01:33 +0200
> 
> This patch is to add
> maint set testsuite mode on/off
> command.

Shouldn't this command be supported on all platforms, and be a no-op
on all of them but MinGW?  Otherwise the test suite will fail for
tests that use this setting, won't it?