minor fix for -u fix

Commit a5d9c40262 had one small problem.
In that function its *argc not argc. This stops pgrep with no commands
from segfaulting, thankyou dejagnu!!

Signed-Off-By: Craig Small <csmall@enc.com.au>

pgrep.c

@@ -564,7 +564,7 @@ int signal_option(int *argc, char **argv)
 {
 	int sig;
 	int i = 1;
-	if (argc > 2 && argv[1][0] == '-') {
+	if (*argc > 2 && argv[1][0] == '-') {
 		sig = signal_name_to_number(argv[i] + 1);
 		if (sig == -1 && isdigit(argv[1][1]))
 			sig = atoi(argv[1] + 1);