check_c_source_compiles("
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#if defined(sun) || defined(__sun__) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
# if defined(__SVR4) || defined(__srv4__)
# define PLATFORM_SOLARIS
# else
# define PLATFORM_SUNOS4
# endif
#endif
#if (defined(_AIX) || defined(__xlC__)) && !defined(_AIX41)
# define PLATFORM_AIX_V3
#endif
#if defined(PLATFORM_SUNOS4) || defined(PLATFORM_AIX_V3) || defined(__BEOS__)
#error \"O_NONBLOCK does not work on this platform\"
#endif
int main()
{
int socket;
int flags = fcntl(socket, F_SETFL, flags | O_NONBLOCK);
}"
HAVE_O_NONBLOCK)