clang -o luac  luac.o print.o liblua.a -lm 
      CC ae.o
      CC adlist.o
      CC quicklist.o
      CC anet.o
      CC server.o
      CC dict.o
      CC sds.o
      CC zmalloc.o
      CC lzf_c.o
      CC lzf_d.o
      CC pqsort.o
      CC zipmap.o
      CC sha1.o
      CC ziplist.o
      CC release.o
      CC networking.o
      CC util.o
      CC object.o
      CC db.o
      CC replication.o
      CC rdb.o
  server.cpp:6565:9: error: use of undeclared identifier 'clock_nanosleep'
          clock_nanosleep(CLOCK_MONOTONIC, 0, &delay, NULL);
          ^
  1 error generated.
  make[1]: *** [server.o] Error 1
  make[1]: *** Waiting for unfinished jobs....
  make: *** [install] Error 2