stringutil: Add early-exit case to ReplaceAll
stringutil: Add early-exit case to ReplaceAll

If both 'replaceands' are the same, the result string can just be returned.

hrydgard/native,unknownbrackets/native,libretro/ppsspp-native,unknownbrackets/native,hrydgard/native,libretro/ppsspp-native,zhykzhykzhyk/ppsspp-native,zhykzhykzhyk/ppsspp-native,zhykzhykzhyk/ppsspp-native,hrydgard/native,zhykzhykzhyk/ppsspp-native,libretro/ppsspp-native,unknownbrackets/native,unknownbrackets/native,libretro/ppsspp-native,hrydgard/native