Unbreak joystick detection.

Index: src/fs-uae/main.c
--- src/fs-uae/main.c.orig
+++ src/fs-uae/main.c
@@ -922,6 +922,7 @@ static void list_joysticks()
     }
     printf("# SDL_NumJoysticks(): %d\n", SDL_NumJoysticks());
     for(int i = 0; i < SDL_NumJoysticks(); i++) {
+        SDL_JoystickOpen(i);
         if (SDL_JoystickName(i)[0] == '\0') {
             printf("J: Unnamed\n");
         }
