The SDL2 winsys will now set the SDL_WINDOW_RESIZABLE flag on the
window before creating it if the resizable property is set on the
onscreen. Note that there doesn't appear to be a way in SDL to change
the flag later so unlike the other winsyses it will only take affect
if it is set before allocating the framebuffer.
The winsys now registers a callback for SDL events so that it can
report window size changes back to the application.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 0dea9aeb897faf029828379b120970477df3c7d5)
9f107ab3fb
