cmake LWS_HAVE_VISIBILITY examples

warmcat/libwebsockets CMakeLists.txt :851 

CHECK_C_COMPILER_FLAG(-fvisibility=hidden LWS_HAVE_VISIBILITY)

c-jimenez/open-ocpp 3rdparty/libwebsockets/CMakeLists.txt :755 

CHECK_C_COMPILER_FLAG(-fvisibility=hidden LWS_HAVE_VISIBILITY)

fluffos/fluffos src/thirdparty/libwebsockets/CMakeLists.txt :738 

CHECK_C_COMPILER_FLAG(-fvisibility=hidden LWS_HAVE_VISIBILITY)