[Bug 599567] mingw32-gcc should not drag in pthreads.h because it's buggy

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=599567
Bug 599567 depends on bug 641423, which changed state.

Bug 641423 Summary: mingw32-gcc installs files both inside and outside the sysroot
https://bugzilla.redhat.com/show_bug.cgi?id=641423

What    |Removed                     |Added
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             Status|ASSIGNED                    |CLOSED
         Resolution|---                         |EOL