extcap: destroy hash tables on exit.

Change-Id: Ia6a1d8a45c36aff7f2bea8bde2ed5f308bddd2e1
Reviewed-on: https://code.wireshark.org/review/19919
Petri-Dish: Roland Knall <rknall@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Dario Lombardo <lomato@gmail.com>
Reviewed-by: Roland Knall <rknall@gmail.com>

extcap.c

@@ -589,6 +589,16 @@ void extcap_cleanup(void)
     {
         g_hash_table_destroy(extcap_prefs_dynamic_vals);
     }
+
+    if (ifaces)
+    {
+        g_hash_table_destroy(ifaces);
+    }
+
+    if (tools)
+    {
+        g_hash_table_destroy(tools);
+    }
 }
 
 void extcap_pref_store(extcap_arg *arg, const char *newval)