Make realloc() support NULL as pointer. Made to allow us to use these routines

  return mem;

}

/* We provide a realloc() that accepts a NULL as pointer, which then

   performs a malloc(). In order to work with ares. */

void *curl_dorealloc(void *ptr, size_t wantedsize,

                     int line, const char *source)

{

  struct memdebug *mem;

  struct memdebug *mem=NULL;

  size_t size = sizeof(struct memdebug)+wantedsize;

  if(countcheck("realloc", line, source))

    return NULL;

  if(ptr)

    mem = (struct memdebug *)((char *)ptr - offsetof(struct memdebug, mem));

  mem=(struct memdebug *)(realloc)(mem, size);

  if(logfile)

    fprintf(logfile, "MEM %s:%d realloc(%p, %d) = %p\n",

    fprintf(logfile, "MEM %s:%d realloc(0x%x, %d) = %p\n",

            source, line, ptr, wantedsize, mem?mem->mem:NULL);

  if(mem) {