re PR rtl-optimization/51978 (ext-elim-1.c ICE on powerpc64)

re PR rtl-optimization/51978 (ext-elim-1.c ICE on powerpc64)

	PR rtl-optimization/51978
	* ree.c (make_defs_and_copies_lists): Change set_pat type
	to const_rtx.
	(combine_reaching_defs): Likewise.
	(struct re_info): Remove.
	(add_removable_extension): Remove x and data arguments,
	add insn, insn_list and def_map.  Use the arguments directly
	instead of using struct re_info.
	(find_removable_extensions): Don't call add_removable_extension
	through note_stores, instead just call it with single_set
	result if non-NULL.
	(find_and_remove_re): Pass curr_cand->expr instead of
	PATTERN (curr_cand->insn) as set_pat argument to
	combine_reaching_defs.

From-SVN: r183567