PR c++/77886
	* pt.c (tsubst_expr) <case CASE_LABEL_EXPR> Copy over
	FALLTHROUGH_LABEL_P flag to the new LABEL_DECL.
	(tsubst_expr) <case LABEL_EXPR>: Likewise.

	* g++.dg/warn/Wimplicit-fallthrough-2.C: New test.

From-SVN: r241700