NAME
        Deallocate -- deallocate a block of memory

   SYNOPSIS
        Deallocate(memHeader, memoryBlock, byteSize)
                   A0         A1           D0

        void Deallocate(struct memheader *,aptr,ulong);

   FUNCTION
        This function deallocates memory by returning it to the appropriate
        private free memory pool.  This function can be used to free an
        entire block allocated with the above function, or it can be used
        to free a sub-block of a previously allocated block.  Sub-blocks
        must be an even multiple of the memory chunk size (currently 8
        bytes).

        This function can even be used to add a new free region to an
        existing memheader, however the extent pointers in the memheader
        will no longer be valid.

        If memoryBlock is not on a block boundary (MEM_BLOCKSIZE) then it
        will be rounded down in a manner compatible with allocate().  note
        that this will work correctly with all the memory allocation
        functions, but may cause surprises if one is freeing only part of a
        region.  The size of the block will be rounded up, so the freed
        block will fill to an even memory block boundary.

   INPUTS
        memHeader - points to the memory header this block is part of.
        memoryBlock - address of memory block to free.
        byteSize - the size of the block in bytes. If NULL, nothing
                   happens.

   SEE ALSO
        allocate(), exec/memory.h