* init.c (build_new): Make backups of any CONSTRUCTORs in init.
	(build_new_1): Use replace_placeholders.
	* tree.c (replace_placeholders_t): Also track whether we've seen a
	placeholder.
	(replace_placeholders, replace_placeholders_r): Adjust.
	* cp-tree.h: Adjust.

From-SVN: r245372