bugfix: fix crash when UE disconnects

Using the basic simulator and valgrind, it was found that
the lack of initialization of those two pointers leads to
some very nasty behavior of some other parts of the system.

common/utils/ocp_itti/intertask_interface.cpp

@@ -51,6 +51,8 @@ extern "C" {
 
   mem_block_t *get_free_mem_block (uint32_t sizeP, const char *caller) {
     mem_block_t *ptr=(mem_block_t *)malloc(sizeP+sizeof(mem_block_t));
+    ptr->next = NULL;
+    ptr->previous = NULL;
     ptr->data=((unsigned char *)ptr)+sizeof(mem_block_t);
     ptr->size=sizeP;
     return ptr;