st/xorg: Work around cursor reference counting bugs in older X servers.

Could result in use of freed memory and consequently random crashes, e.g. on
screen resize.
(cherry picked from commit 21c91b410a2a2cbf8eb677e59e3322f86320f2b0)

Conflicts:

	src/gallium/state_trackers/xorg/xorg_tracker.h

src/gallium/state_trackers/xorg/xorg_crtc.c

@@ -275,7 +275,21 @@ err_bo_destroy:
 static void
 crtc_load_cursor_argb(xf86CrtcPtr crtc, CARD32 * image)
 {
+    xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(crtc->scrn);
     modesettingPtr ms = modesettingPTR(crtc->scrn);
+
+    /* Older X servers have cursor reference counting bugs leading to use of
+     * freed memory and consequently random crashes. Should be fixed as of
+     * xserver 1.8, but this workaround shouldn't hurt anyway.
+     */
+    if (config->cursor)
+       config->cursor->refcnt++;
+
+    if (ms->cursor)
+       FreeCursor(ms->cursor, None);
+
+    ms->cursor = config->cursor;
+
     if (ms->screen)
 	crtc_load_cursor_argb_ga3d(crtc, image);
 #ifdef HAVE_LIBKMS

src/gallium/state_trackers/xorg/xorg_driver.c

@@ -922,6 +922,11 @@ drv_close_screen(int scrnIndex, ScreenPtr pScreen)
 	drv_leave_vt(scrnIndex, 0);
     }
 
+    if (ms->cursor) {
+       FreeCursor(ms->cursor, None);
+       ms->cursor = NULL;
+    }
+
     if (cust && cust->winsys_screen_close)
 	cust->winsys_screen_close(cust);
 

src/gallium/state_trackers/xorg/xorg_tracker.h

@@ -90,6 +90,7 @@ typedef struct _modesettingRec
 
     Bool noAccel;
     Bool SWCursor;
+    CursorPtr cursor;
     CloseScreenProcPtr CloseScreen;
 
     /* Broken-out options. */