Use pymake [or some sort of parallel build] when building xulrunner on windows

[johnmurrayvi]

I saw that pymake supported concurrent compilation jobs and does not have deadlock issues on Windows. I'm assuming that problem is why builds aren't using some form of parallel compilation as of now. If not pymake, then maybe there's something else that could be used. Either way, it would definitely be nice to not wait 2+ hours on xulrunner debug and release builds.

[mook]

Yeah, the default mozconfigs should be using -j of some sort on non-Win32
platforms already; pymake or a patched GNU make 4 might allow parallel
builds on Windows too.

[johnmurrayvi]

I'm gonna try to get this functional, so I'll assign myself.

[johnmurrayvi]

Looks like this may be fixed upstream now with "mozmake":
https://bugzilla.mozilla.org/show_bug.cgi?id=927213

Also, I forgot to add:
ac63d38
The -jN flag was being hardcoded to -j1 apparently.

[johnmurrayvi]

Changing this to Windows only