cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration sched/sched_rr_get_interval.c -o sched/sched_rr_get_interval -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
sched/sched_rr_get_interval.c:13:18: error: variable has incomplete type 'struct timespec'
   13 |         struct timespec ts;
      |                         ^
sched/sched_rr_get_interval.c:13:9: note: forward declaration of 'struct timespec'
   13 |         struct timespec ts;
      |                ^
sched/sched_rr_get_interval.c:14:7: error: call to undeclared function 'sched_rr_get_interval'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   14 |         if ( sched_rr_get_interval(0, &ts) < 0 )
      |              ^
2 errors generated.