qt_windows.h - windows.h include missing extern "C"

In src/corelib/global/qt_windows.h the windows.h include is missing an extern "C" linkage declaration:

#include <windows.h>

This causes a compile error on MinGW-w64 GCC 4.5.1 (http://www.mail-archive.com/mingw-w64-public@lists.sourceforge.net/msg00952.html).

It should be:

#ifdef __cplusplus
extern "C" {
#endif
#include <windows.h>
#ifdef __cplusplus
}
#endif