* Allocates memory of for an array of `items' elements of `size' bytes
* and returns pointer to the allocated memory area. The memory area is
* also zeroed. Free the memory by calling silc_free. Returns NULL on
* Allocates memory of for an array of `items' elements of `size' bytes
* and returns pointer to the allocated memory area. The memory area is
* also zeroed. Free the memory by calling silc_free. Returns NULL on