MSC: int _heapwalk( struct _heapinfo *entry )

	MSC: int _bheapwalk( _segment seg, struct _heapinfo *entry )
	MSC: int _fheapwalk( struct _heapinfo *entry )
	MSC: int _nheapwalk( struct _heapinfo *entry )

	- prototype in malloc.h

	- walks the heap for each entry specified and returns information
	  about the entry via the other fields of the _heapinfo structure
	- heapwalk maps to the other functions depending on memory model
	- returns one of the following:

	  _HEAPOK	heap is ok
	  _HEAPBADBEGIN initials allocation header couldn't be found
	  _HEAPBADNODE	heap/node has been damaged
	  _HEAPEMPTY	heap has not been initialized
	  _HEAPBADPTR	parameter does not contain valid pointer to heap
	  _HEAPEND	end of help found w/o problem

	struct _heapinfo
	   int	  _far *_pentry;   	- heap entry pointer
	   size_t _size;	   	- size of heap entry
	   int	  _useflag;	   	- entry in use return value

	- see	heapchk()   heapset()