The logic of fetchnetstat_sysctl() isn't too complex: if idx is 0,

we set and use xtp; if idx is 1, we set and use xip; the other cases
are impossible.  However, GCC cannot see that xip and xtp are always
initialized before use because they are initialized and used in
different if/else blocks.  So setting them to NULL at the very
beginning won't hurt.

usr.bin/systat/netstat.c

@@ -252,8 +252,8 @@ fetchnetstat_sysctl()
 	struct xinpgen *inpg;
 	char *cur, *end;
 	struct inpcb *inpcb;
-	struct xinpcb *xip;
-	struct xtcpcb *xtp;
+	struct xinpcb *xip = NULL;
+	struct xtcpcb *xtp = NULL;
 	int plen;
 	size_t lsz;