cmake LWS_HAVE_UNISTD_H examples

warmcat/libwebsockets CMakeLists.txt :681 

CHECK_C_SOURCE_COMPILES("#include <unistd.h>\nvoid main(void) { while(1) ; } void xxexit(void){}" LWS_HAVE_UNISTD_H)

c-jimenez/open-ocpp 3rdparty/libwebsockets/CMakeLists.txt :645 

CHECK_INCLUDE_FILE(unistd.h LWS_HAVE_UNISTD_H)

fluffos/fluffos src/thirdparty/libwebsockets/CMakeLists.txt :628 

CHECK_INCLUDE_FILE(unistd.h LWS_HAVE_UNISTD_H)