build failure on master with NO_DHCPv6 and fix....

Hi Simon,

master has a build error when building without HAVE_DHCPv6

option.c: In function 'dhcp_context_free':
option.c:1042:15: error: 'struct dhcp_context' has no member named 'template_interface'
       free(ctx->template_interface);

Sadly, need to put in a little conditional compilation ifdef'erey

Simplest patch in the world attached

Cheers,

Kevin D-B

012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A

From 061eb8599636bb360e0b7fa5986935b86db39497 Mon Sep 17 00:00:00 2001
From: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Date: Mon, 10 Dec 2018 10:07:33 +0000
Subject: [PATCH] option: fix non DHCPv6 build error

option.c: In function 'dhcp_context_free':
option.c:1042:15: error: 'struct dhcp_context' has no member named 'template_interface'
       free(ctx->template_interface);
		^~

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

src/option.c

@@ -1039,7 +1039,9 @@ static void dhcp_context_free(struct dhcp_context *ctx)
     {
       dhcp_netid_free(ctx->filter);
       free(ctx->netid.net);
+#ifdef HAVE_DHCP6
       free(ctx->template_interface);
+#endif
       free(ctx);
     }
 }