hostid: improve extremely unreadable parts

*: remove checks of sigaction and sigprocmask results
 in cases where they clearly can't fail:
 sigaction(known_good_sig)
 sigprocmask(known_good_how)

    text           data     bss     dec     hex filename
-    393              4       0     397     18d libc/pwd_grp/lckpwdf.o
+    382              4       0     386     182 libc/pwd_grp/lckpwdf.o
-     56              0       0      56      38 libc/signal/sigblock.o
+     44              0       0      44      2c libc/signal/sigblock.o
-    211              0       0     211      d3 libc/signal/sigset.o
+    202              0       0     202      ca libc/signal/sigset.o
-     56              0       0      56      38 libc/signal/sigsetmask.o
+     44              0       0      44      2c libc/signal/sigsetmask.o
-    309              0       0     309     135 libc/unistd/sleep.o
+    256              0       0     256     100 libc/unistd/sleep.o

1 files changed, 1 insertions, 0 deletions

diff --git a/libc/signal/sysv_signal.c b/libc/signal/sysv_signal.c
index f573482f9..118094b27 100644
--- a/libc/signal/sysv_signal.c
+++ b/libc/signal/sysv_signal.c
@@ -49,6 +49,7 @@ __sighandler_t __sysv_signal (int sig, __sighandler_t handler)
   act.sa_handler = handler;
   __sigemptyset (&act.sa_mask);
   act.sa_flags = (SA_ONESHOT | SA_NOMASK | SA_INTERRUPT) & ~SA_RESTART;
+  /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
   if (sigaction (sig, &act, &oact) < 0)
     return SIG_ERR;