Double freeing pointers

I believe that most of double freeing of pointer core dump issues can simple by resolved by altering the axutil_allocator_free_impl function

change

void AXIS2_CALL
axutil_allocator_free_impl(
axutil_allocator_t * allocator,
void *ptr)
{
free(ptr);
}

to

void AXIS2_CALL
axutil_allocator_free_impl(
axutil_allocator_t * allocator,
void *ptr)
{
free(ptr);
ptr = NULL;
}