[PATCH] Catch errors with sigaddset(3) in sigaddset (sighold)

[Garrett Cooper]

    sighold(3) doesn't determine whether or not the signal added is
valid today (and sigprocmask doesn't verify that either). This fixes
that.
Thanks,
-Garrett

Index: sigcompat.c
===================================================================
--- sigcompat.c	(revision 210226)
+++ sigcompat.c	(working copy)
@@ -131,7 +131,8 @@
 	sigset_t set;

 	sigemptyset(&set);
-	sigaddset(&set, sig);
+	if (sigaddset(&set, sig) == -1)
+		return (-1);
 	return (_sigprocmask(SIG_BLOCK, &set, NULL));
 }