libselinux: utils: avcstat: clear sa_mask set

We were leaving random stack garbage in sa.sa_mask.  Clear it the way
one should.  (spotted by coveriety)

Signed-off-by: Eric Paris <eparis@redhat.com>

libselinux/utils/avcstat.c

@@ -139,6 +139,7 @@ int main(int argc, char **argv)
 
 	sa.sa_handler = sighandler;
 	sa.sa_flags = SA_RESTART;
+	sigemptyset(&sa.sa_mask);
 
 	i = sigaction(SIGWINCH, &sa, NULL);
 	if (i < 0)