cc -pipe -O   -pthread  -Wall -Wextra -Werror=implicit-function-declaration threads/cnd_wait.c -o threads/cnd_wait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread -lrt  -lrt -lcrypt
threads/cnd_wait.c:3:10: fatal error: threads.h: No such file or directory
 #include <threads.h>
          ^~~~~~~~~~~
compilation terminated.