update CHANGELOG and fix coding style (fixed bug #39355 SNMP Memory Leak in case of error)

CHANGELOG

@@ -117,6 +117,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2014-09-03: Simon Goldschmidt
+  * msg_in.c: fixed bug #39355 SNMP Memory Leak in case of error
+
   2014-09-02: Simon Goldschmidt
   * err.h/.c, sockets.c, api_msg.c: fixed bug #43110 call getpeername() before
     listen() will cause a error

src/core/snmp/msg_in.c

@@ -110,11 +110,10 @@ snmp_error_response(struct snmp_msg_pstat *msg_ps, u8_t error)
   struct snmp_varbind *vbi = msg_ps->invb.head;
   struct snmp_varbind *vbo = msg_ps->outvb.head;
   for (v=0; v<msg_ps->vb_idx; v++) {
-    if (vbi->ident != NULL )
-    {
+    if (vbi->ident != NULL) {
+      /* free previously allocated value before overwriting the pointer */
       memp_free(MEMP_SNMP_VALUE, vbi->ident);
     }
-
     vbi->ident_len = vbo->ident_len;
     vbo->ident_len = 0;
     vbi->ident = vbo->ident;