* heap.cc (heap_init): Rewrite initial heap allocation to use addresses

	* heap.cc (heap_init): Rewrite initial heap allocation to use addresses
	beyond 0x20000000.  Explain why and how.
	* shared.cc (shared_info::heap_slop_size): Remove.
	* shared_info.h (class shared_info): Remove heap_slop_inited and
	heap_slop members.  Remove heap_slop_size declaration.
	(CURR_SHARED_MAGIC): Update.
	* wincap.cc: Throughout, drop heapslop.
	* wincap.h (struct wincaps): Drop heapslop.