finger.c set pointer to NULL

[Brad Tilley]

Not sure this is an acceptable patch. Certainly not required, but
maybe good practice?

# cvs diff -Nup finger.c
Index: finger.c
===================================================================
RCS file: /cvs/src/usr.bin/finger/finger.c,v
retrieving revision 1.18
diff -N -u -p finger.c
--- finger.c    12 Nov 2009 15:33:21 -0000      1.18
+++ finger.c    10 Dec 2009 00:33:02 -0000
@@ -246,6 +246,8 @@ net:        for (pn = nethead; pn; pn = pn->next) {
        }

        free(used);
+       used = NULL;
+
        if (entries == 0)
                return;