Handle WM_CLOSE messages in overlay helper.
Handle WM_CLOSE messages in overlay helper.

When Qt terminates a QProcess via the terminate()
method, it sends a WM_CLOSE message.

However, the overlay helper did not know of WM_CLOSE,
so it would quietly ignore it.

This commit teaches the overlay helper to exit on
WM_CLOSE.

mbax/mumble,unascribed/mumble,Githlar/mumble,unascribed/mumble,mbax/mumble,ccpgames/mumble,Zopieux/mumble,niko20010/mumble,richard227/mumble,bheart/mumble,LuAPi/mumble,bheart/mumble,Keridos/mumble,LuAPi/mumble,unascribed/mumble,LuAPi/mumble,Zopieux/mumble,feld/mumble,Keridos/mumble,unascribed/mumble,feld/mumble,feld/mumble,Zopieux/mumble,Natenom/mumble,ccpgames/mumble,LuAPi/mumble,niko20010/mumble,richard227/mumble,SuperNascher/mumble,bheart/mumble,Natenom/mumble,Natenom/mumble,bheart/mumble,LuAPi/mumble,feld/mumble,Githlar/mumble,Zopieux/mumble,SuperNascher/mumble,ccpgames/mumble,Keridos/mumble,Keridos/mumble,Natenom/mumble,unascribed/mumble,richard227/mumble,ccpgames/mumble,LuAPi/mumble,Lartza/mumble,feld/mumble,austinliou/mumble,Githlar/mumble,Githlar/mumble,austinliou/mumble,austinliou/mumble,SuperNascher/mumble,richard227/mumble,Keridos/mumble,Lartza/mumble,feld/mumble,richard227/mumble,richard227/mumble,austinliou/mumble,ccpgames/mumble,LuAPi/mumble,feld/mumble,austinliou/mumble,mbax/mumble,niko20010/mumble,Natenom/mumble,mbax/mumble,Natenom/mumble,SuperNascher/mumble,Zopieux/mumble,Keridos/mumble,niko20010/mumble,Zopieux/mumble,unascribed/mumble,ccpgames/mumble,Githlar/mumble,LuAPi/mumble,Keridos/mumble,bheart/mumble,niko20010/mumble,mbax/mumble,austinliou/mumble,Githlar/mumble,Lartza/mumble,niko20010/mumble,richard227/mumble,Lartza/mumble,SuperNascher/mumble,LuAPi/mumble,Keridos/mumble,bheart/mumble,richard227/mumble,Natenom/mumble,Zopieux/mumble,Githlar/mumble,mbax/mumble,mbax/mumble,mbax/mumble,ccpgames/mumble,austinliou/mumble,SuperNascher/mumble,Natenom/mumble,ccpgames/mumble,Lartza/mumble,SuperNascher/mumble,Lartza/mumble,austinliou/mumble,bheart/mumble,bheart/mumble,niko20010/mumble,Githlar/mumble,feld/mumble,Zopieux/mumble,Lartza/mumble,Lartza/mumble,unascribed/mumble,unascribed/mumble,niko20010/mumble,SuperNascher/mumble,SuperNascher/mumble