[Releasing] 4.8.3_rc2 regression: pkg-config broken for mingw

[Mark Brand]

Mark Brand wrote:
> Just noticed a new regression in 4.8.3_rc2.  Commit 
> c7d5071afc6c76925c90ff35041dc4eb86511271 breaks pkg-config for MinGW. 


Fixes proposed:

Qt 4.8: https://codereview.qt-project.org/34663

Qt 5.0: https://codereview.qt-project.org/34661

Mark