Correctly handle Unicode Replacement Characters

sc2/src/libs/input/sdl/input.c

@@ -479,7 +479,7 @@ ProcessInputEvent (const SDL_Event *Event)
 				/* Out of the BMP, won't fit in a UniChar */
 				/* Use the replacement character instead */
 				map_key = 0xFFFD;
-				while (Event->text.text[i] > 0x7F)
+				while ((UniChar)Event->text.text[i] > 0x7F)
 				{
 					++i;
 				}