clang -O2  -Wall -Wextra -Werror=implicit-function-declaration signal/pthread_kill.c -o signal/pthread_kill -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
signal/pthread_kill.c:4:10: fatal error: 'pthread.h' file not found
#include <pthread.h>
         ^
1 error generated.