app layer ftp fix (mem leak)

src/app-layer-ftp.c

@@ -248,6 +248,9 @@ static void *FTPStateAlloc(void) {
 }
 
 static void FTPStateFree(void *s) {
+    FtpState *fstate = (FtpState *) s;
+    if (fstate->port_line != NULL)
+        SCFree(fstate->port_line);
     SCFree(s);
 #ifdef DEBUG
     SCMutexLock(&ftp_state_mem_lock);