EGL: Properly set parent window.

In X with EGL and WX frontend enabled, running the emulator created
two windows. This was because the parent window was set incorrectly.

Source/Core/DolphinWX/GLInterface/EGL.cpp

@@ -173,6 +173,7 @@ bool cInterfaceEGL::Create(void *&window_handle)
 	else
 		eglBindAPI(EGL_OPENGL_ES_API);
 
+	GLWin.parent = (Window) window_handle;
 
 	if (!Platform.Init(config))
 		return false;