middle-end/94188 fix fold of addr expression generation

This adds a missing type conversion to build_fold_addr_expr and adjusts
fallout - build_fold_addr_expr was used as a convenience to build an
ADDR_EXPR but some callers do not expect the result to be simplified
to something else.

2020-03-18  Richard Biener  <rguenther@suse.de>

	PR middle-end/94188
	* fold-const.c (build_fold_addr_expr): Convert address to
	correct type.
	* asan.c (maybe_create_ssa_name): Strip useless type conversions.
	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Use build1
	to build the ADDR_EXPR which we don't really want to simplify.
	* tree-ssa-dom.c (record_equivalences_from_stmt): Likewise.
	* tree-ssa-loop-im.c (gather_mem_refs_stmt): Likewise.
	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Likewise.
	(simplify_builtin_call): Strip useless type conversions.
	* tree-ssa-strlen.c (new_strinfo): Likewise.

	* gcc.dg/pr94188.c: New testcase.