core: sip_msg_shm_clone: clone parsed maxforwards value in shm

maxfwd module modified the msg buf directly instead of adding a lump. In
addition it is filling the parsed value of the header field.

Clone this field into shm so later code can at least determine if the msg
has been mangled so it can retreive the original value of the header.

(cherry picked from commit 42f506c08073c5f8ca84f1f12ea9e6c820f162d8)

sip_msg_clone.c

@@ -743,6 +743,7 @@ struct sip_msg*  sip_msg_shm_clone( struct sip_msg *org_msg, int *sip_msg_len,
 		case HDR_MAXFORWARDS_T:
 			if (!HOOK_SET(maxforwards)) {
 				new_msg->maxforwards = new_hdr;
+				new_msg->maxforwards->parsed = hdr->parsed;
 			}
 			break;
 		case HDR_ROUTE_T: