pixman: fix qemu_default_pixman_format (32bpp non-native endian)

Bug breaks SDL display of bigendian guests on little endian hosts.

Reported-by: BALATON Zoltan <balaton@eik.bme.hu>
Reported-by: Valentin Manea <valentin.manea@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/qemu-pixman.c

@@ -80,7 +80,7 @@ pixman_format_code_t qemu_default_pixman_format(int bpp, bool native_endian)
         case 24:
             return PIXMAN_b8g8r8;
         case 32:
-            return PIXMAN_b8g8r8a8;
+            return PIXMAN_b8g8r8x8;
         break;
         }
     }