!86 fix killpg and waitid

Merge pull request !86 from wangjianjun/waitid

porting/liteos_a/user/src/process/waitid.c

-#include <sys/wait.h>
-#include <unsupported_api.h>
-#include "syscall.h"
-
-int waitid(idtype_t type, id_t id, siginfo_t *info, int options)
-{
-	unsupported_api(__FUNCTION__);
-	return syscall_cp(SYS_waitid, type, id, info, options, 0);
-}

porting/liteos_a/user/src/signal/killpg.c

-#include <signal.h>
-#include <errno.h>
-#include <unsupported_api.h>
-
-int killpg(pid_t pgid, int sig)
-{
-	unsupported_api(__FUNCTION__);
-	if (pgid < 0) {
-		errno = EINVAL;
-		return -1;
-	}
-	return kill(-pgid, sig);
-}