sdl2: skip init without outputs

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Cole Robinson <crobinso@redhat.com>
Message-id: 1464790116-32405-1-git-send-email-kraxel@redhat.com
(cherry picked from commit 8efa5f2)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

ui/sdl2.c

@@ -794,6 +794,9 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)
         }
     }
     sdl2_num_outputs = i;
+    if (sdl2_num_outputs == 0) {
+        return;
+    }
     sdl2_console = g_new0(struct sdl2_console, sdl2_num_outputs);
     for (i = 0; i < sdl2_num_outputs; i++) {
         QemuConsole *con = qemu_console_lookup_by_index(i);