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

0 files changed, 0 insertions, 0 deletions