ignore blank lines in addition to comments

fixes pr#1660 from wilfried@telia.com .. Thanks!

src/etc/netstart

@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$OpenBSD: netstart,v 1.75 2001/01/10 22:17:10 jason Exp $
+#	$OpenBSD: netstart,v 1.76 2001/02/06 23:05:45 todd Exp $
 
 # Returns true if $1 contains only alphanumerics
 isalphanumeric() {
@@ -123,7 +123,7 @@ for hn in /etc/hostname.*; do
 	# $af can be "dhcp", "up", "rtsol", an address family, commands, or
 	# a comment.
 	case "$af" in
-	"#"*) # skip comments
+	"#"*|"") # skip comments and empty lines
 	    continue
 	    ;;
 	"!"*) # parse commands