This is called by COS to deallocate memory previously allocated. The simplest implementation is to use the default platform's standard free call, ignoring the hint.
This callback must not be NULL.
Parameters
ptr
The pointer, as returned from a previous call to the Alloc callback. This may be NULL, in which case no action should be taken.
hint
A hint to indicate the type of memory that is being freed. See DOSMemoryHint.