Reset savex, savey, and savegc in hardreset

While refactoring scriptclass::startgamemode, I noticed that these
variables weren't being reset. Fortunately, this doesn't seem to have
affected anything because they get overwritten one way or another in
startgamemode. But it's good just to be defensive and reset them anyway.

They are not reset in 2.2 or 2.0 glitchrunner mode because dying during
exiting to the menu is needed for credits warp, and that means the
checkpoint position needs to be maintained through.

desktop_version/src/Script.cpp

@@ -3163,6 +3163,9 @@ void scriptclass::hardreset(void)
         // Ironically, resetting more variables makes the janky fadeout system in glitchrunnermode even more glitchy
         game.saverx = 0;
         game.savery = 0;
+        game.savex = 0;
+        game.savey = 0;
+        game.savegc = 0;
     }
     game.savecolour = 0;