This function allocates memory in a similar manner to the
standard C "calloc" function, but with improved security
(against memory leaks, etc.) and with error reporting. It also
fills the allocated memory with zeros.
Like astMalloc, it allows zero-sized memory allocation
(without error), resulting in a NULL returned pointer value.
void astCalloc( size_t nmemb, size_t size )
The number of array elements for which memory is to be allocated.
The size of each array element, in bytes.
If successful, the function returns a pointer to the start of
the allocated memory region. If the size allocated is zero, this
will be a NULL pointer.
A pointer value of NULL is returned if this function is
invoked with the global error status set or if it fails for any