MSC: void _bfree( _segment seg, void _based(void) *block )
	  MSC: void _ffree( void far *block )
	  MSC: void _nfree( void near *block )


	- prototype in malloc.h

	- block = previously allocated buffer
	- in large data memory models free() maps to _ffree()
	- in small data memory models free() maps to _nfree()
	- NULL pointer parameter is ignored