cmake HAVE_IPO_OUTPUT examples

OpenMW/openmw CMakeLists.txt :574 

check_ipo_supported(RESULT HAVE_IPO OUTPUT HAVE_IPO_OUTPUT)

OpenMW/openmw CMakeLists.txt :579 

message(WARNING "Requested option OPENMW_LTO_BUILD not supported by this compiler: ${HAVE_IPO_OUTPUT}")