gdkwindow-win32.c: Fix GLES glitches during un-fullscreen

We also need to force redraw of the whole window when we are using
EGL/ANGLE during un-fullscreen, so that we do not get glitches in the
resulting window.
2 jobs for gtk3.win.egl.unfullscreen in 9 minutes and 50 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #249041
build

00:09:50

manual #249042
win32 allowed to fail manual
msys2-mingw32