qmake generated Makefles for mingw32 do not add DEFINES to windres.exe command line

Just compare MingwMakefileGenerator::writeRcFilePart() and Win32MakefileGenerator::writeRcFilePart().

The nmake generator add $(DEFINES) whereas the mingw one does not and this breaks some apps, since .rc files are pre-processed like normal .c files.

Adding '<< " $(DEFINES"' as the last argument to the windres.exe invocation fixes this problem - see attached patch