[SP] A more effective icon/name fix

MACOSX_BUNDLE_ICON_FILE, MACOSX_BUNDLE_BUNDLE_NAME and
MACOSX_BUNDLE_DISPLAY_NAME can only be set once in a cmakelists, so
unless it’s done like this there will be problems when also building
JK2.
[JK2SP] OSX app bundle for JK2SP now has name/icon