X11: don't block on a ConfigureNotify event during SDL_SetWindowBordered(). Unity's window manager is (legitimately, since it moves the client window's position) sending one, and SDL was incorrectly trying to mask it out. Other window managers (KWin, apparently) don't move the window and would hang here indefinitely. Fixes Bugzilla #3052.
diff --git a/src/video/x11/SDL_x11window.c b/src/video/x11/SDL_x11window.c
index 6db968a..d5f083e 100644
--- a/src/video/x11/SDL_x11window.c
+++ b/src/video/x11/SDL_x11window.c
@@ -864,7 +864,6 @@ X11_SetWindowBordered(_THIS, SDL_Window * window, SDL_bool bordered)
SetWindowBordered(display, displaydata->screen, data->xwindow, bordered);
X11_XFlush(display);
- X11_XIfEvent(display, &event, &isConfigureNotify, (XPointer)&data->xwindow);
if (visible) {
XWindowAttributes attr;