Fix wrong Tower music when toggling Flip Mode from in-game options

The music for the Tower is supposed to be ecroF evitisoP in Flip Mode,
and Positive Force when not in Flip Mode. However, if you go to the
options from the pause menu and toggle Flip Mode, the music isn't
changed.

Fixing this is pretty simple, just check the current area if not in a
custom level and play the correct track accordingly when toggling Flip
Mode from in-game.

desktop_version/src/Input.cpp

@@ -635,6 +635,23 @@ void menuactionpress()
             {
                 music.playef(11);
             }
+            // Fix wrong area music in Tower (Positive Force vs. ecroF evitisoP)
+            if (map.custommode)
+            {
+                break;
+            }
+            int area = map.area(game.roomx, game.roomy);
+            if (area == 3 || area == 11)
+            {
+                if (graphics.setflipmode)
+                {
+                    music.play(9); // ecroF evitisoP
+                }
+                else
+                {
+                    music.play(2); // Positive Force
+                }
+            }
         }
             break;
         }