sched/signal: Fix nxsig_ismember() return value behavior

nxsig_ismember() has a return type of int, but the current
implementation returns a boolean value, which is incorrect.

All callers should determine membership by checking whether
the return value is 1 or 0, which is also consistent with the POSIX sigismember() API.

Signed-off-by: Chengdong Wang wangchengdong@lixiang.com

sched/group/group_signal.c

@@ -127,7 +127,7 @@ static int group_signal_handler(pid_t pid, FAR void *arg)
 
   /* Is this signal unblocked on this thread? */
 
-  if (!nxsig_ismember(&tcb->sigprocmask, info->siginfo->si_signo) &&
+  if ((nxsig_ismember(&tcb->sigprocmask, info->siginfo->si_signo) != 1) &&
       !info->ptcb && tcb != info->atcb)
     {
       /* Yes.. remember this TCB if we have not encountered any

sched/signal/sig_dispatch.c

@@ -550,7 +550,7 @@ int nxsig_tcbdispatch(FAR struct tcb_s *stcb, siginfo_t *info,
 
       if (stcb->task_state == TSTATE_WAIT_SIG &&
           (masked == 0 ||
-           nxsig_ismember(&stcb->sigwaitmask, info->si_signo)))
+           (nxsig_ismember(&stcb->sigwaitmask, info->si_signo) == 1)))
         {
           if (stcb->sigunbinfo != NULL)
             {

sched/signal/sig_lowest.c

@@ -50,7 +50,7 @@ int nxsig_lowest(sigset_t *set)
 
   for (signo = MIN_SIGNO; signo <= MAX_SIGNO; signo++)
     {
-      if (nxsig_ismember(set, signo))
+      if (nxsig_ismember(set, signo) == 1)
         {
           return signo;
         }

sched/signal/sig_timedwait.c

@@ -419,7 +419,7 @@ int nxsig_timedwait(FAR const sigset_t *set, FAR struct siginfo *info,
            * that we were waiting for?
            */
 
-          if (nxsig_ismember(set, rtcb->sigunbinfo->si_signo))
+          if (nxsig_ismember(set, rtcb->sigunbinfo->si_signo) == 1)
             {
               /* Yes.. the return value is the number of the signal that
                * awakened us.