remove checks for "impossible" errors,

clarify uses of unoptimized sigXXX ops (they check signo),
use faster sigops where approproate.

    text           data     bss     dec     hex filename
-     68              0       0      68      44 libc/signal/sighold.o
+     63              0       0      63      3f libc/signal/sighold.o
-    114              0       0     114      72 libc/signal/sigintr.o
+    110              0       0     110      6e libc/signal/sigintr.o
-    113              0       0     113      71 libc/signal/sigpause.o
+    108              0       0     108      6c libc/signal/sigpause.o
-     68              0       0      68      44 libc/signal/sigrelse.o
+     63              0       0      63      3f libc/signal/sigrelse.o

1 files changed, 2 insertions, 5 deletions

diff --git a/libc/signal/sigintr.c b/libc/signal/sigintr.c
index 351c82b75..23f87e199 100644
--- a/libc/signal/sigintr.c
+++ b/libc/signal/sigintr.c
@@ -34,7 +34,7 @@ int siginterrupt (int sig, int interrupt)
 #ifdef	SA_RESTART
   struct sigaction action;
 
-  if (sigaction (sig, (struct sigaction *) NULL, &action) < 0)
+  if (sigaction (sig, NULL, &action) < 0)
     return -1;
 
   if (interrupt)
@@ -48,10 +48,7 @@ int siginterrupt (int sig, int interrupt)
       action.sa_flags |= SA_RESTART;
     }
 
-  if (sigaction (sig, &action, (struct sigaction *) NULL) < 0)
-    return -1;
-
-  return 0;
+  return sigaction (sig, &action, NULL);
 #else
   __set_errno (ENOSYS);
   return -1;