check_c_source_compiles (
                                 "#include <sys/types.h>
                                  #include <sys/mman.h>
                                 int main () {
                                        mmap (0, 1024, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
                                        return 0;
                                 }"
                                 PLIBSYS_MMAP_HAS_MAP_ANONYMOUS
                                )