glretrace: Don't request alpha bits pixel formats on Windows.
glretrace: Don't request alpha bits pixel formats on Windows.

To prevent ChoosePixelFormat from picking up software pixel formats.

swq0553/apitrace,swq0553/apitrace,apitrace/apitrace,EoD/apitrace,tuanthng/apitrace,joshua5201/apitrace,EoD/apitrace,EoD/apitrace,trtt/apitrace,EoD/apitrace,surround-io/apitrace,surround-io/apitrace,surround-io/apitrace,schulmar/apitrace,trtt/apitrace,trtt/apitrace,EoD/apitrace,joshua5201/apitrace,apitrace/apitrace,swq0553/apitrace,swq0553/apitrace,trtt/apitrace,schulmar/apitrace,tuanthng/apitrace,surround-io/apitrace,surround-io/apitrace,schulmar/apitrace,joshua5201/apitrace,apitrace/apitrace,swq0553/apitrace,tuanthng/apitrace,apitrace/apitrace,joshua5201/apitrace,joshua5201/apitrace,schulmar/apitrace,trtt/apitrace,schulmar/apitrace,tuanthng/apitrace,tuanthng/apitrace