porting里新增接口sched_setscheduler，修改musl_src.gni，新增对应测试用例并修改test_src_functional.gni

Signed-off-by: caifuzhou <504631861@qq.com>

libc-test/src/functional/sched_setscheduler.c

 #include <sched.h>
 #include <stdio.h>
 #include <errno.h>
-#include <sys/types.h>
-#include <unistd.h>
 #include <string.h>
 #include "test.h"