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, 3 deletions

diff --git a/libc/signal/sigrelse.c b/libc/signal/sigrelse.c
index f5ee6fedc..1a7141ac5 100644
--- a/libc/signal/sigrelse.c
+++ b/libc/signal/sigrelse.c
@@ -30,10 +30,9 @@ int sigrelse (int sig)
   sigset_t set;
 
   /* Retrieve current signal set.  */
-  if (sigprocmask (SIG_SETMASK, NULL, &set) < 0)
-    return -1;
+  sigprocmask (SIG_SETMASK, NULL, &set); /* can't fail */
 
-  /* Remove the specified signal.  */
+  /* Bound-check sig, remove it from the set.  */
   if (sigdelset (&set, sig) < 0)
     return -1;