Update config.py to honor CXXFLAGS from env
Update config.py to honor CXXFLAGS from env

mklight/eCMD,mklight/eCMD,open-power/eCMD,open-power/eCMD,open-power/eCMD,open-power/eCMD,mklight/eCMD,open-power/eCMD,mklight/eCMD,mklight/eCMD