wayland: Enable text input even when the text input protocol is not available.

Even without the text input protocol, basic text can still be obtained from individual keys and the composition system.

src/video/wayland/SDL_waylandkeyboard.c

@@ -183,11 +183,12 @@ bool Wayland_StartTextInput(SDL_VideoDevice *_this, SDL_Window *window, SDL_Prop
                 Wayland_SeatUpdateTextInput(seat);
             }
         }
-
-        return true;
     }
 
-    return SDL_SetError("wayland: cannot enable text input; compositor lacks support for the required zwp_text_input_v3 protocol");
+    /* Always return true, even if the text input protocol isn't supported, as basic
+     * text can still be obtained from individual keys and composition system.
+     */
+    return true;
 }
 
 bool Wayland_StopTextInput(SDL_VideoDevice *_this, SDL_Window *window)