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, 2 insertions, 0 deletions

diff --git a/libc/signal/sigwait.c b/libc/signal/sigwait.c
index 64a889f7b..bed7f979a 100644
--- a/libc/signal/sigwait.c
+++ b/libc/signal/sigwait.c
@@ -74,6 +74,8 @@ int __sigwait (const sigset_t *set, int *sig)
         __sigdelset (&tmp_mask, this);
 
         /* Register temporary action handler.  */
+        /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
+        /* (so, will it work correctly if set has, say, SIGSTOP?) */
         if (sigaction (this, &action, &saved[this]) != 0)
           goto restore_handler;
       }