gdkdisplay-win32.c: Don't retry WGL initialization

gdkdisplay-win32.c: Don't retry WGL initialization

On Windows, GLES is not that widely available unless one installs wrapper
libraries such as libANGLE, so GLES/EGL support on Windows is used more like
a fallback mode if Desktop OpenGL (WGL) support is inadequate on the system.

Hence, unless one forces WGL or EGL, we will first try to initialize WGL, and
then try to initialize GLES if enabled and if WGL initialization failed, and
then just return whatever the last result we can obtain from these
initialization attempts, since unlike X11 EGL contexts, we do not have
separate modes for WGL except for legacy and non-legacy contexts.