Logic for detecting working on deps with spaces imperfect

[mohawk2]

The MM_Win32 override of quote_dep correctly knows gmake can work on deps with spaces, so falls back to the MM_Any version. That calls can_dep_space which is overridden in MM_Win32 to return true only if GetShortPathName works. When short pathnames are turned off, this gives a false negative.

A simple fix would be to not try the short pathname if on gmake, but a slightly better solution might be to separate the logic of knowing if can shorten paths, from whether one should even try.