tree-inline: Fix VLA handling [PR95552]

tree-inline: Fix VLA handling [PR95552]

The problem in this testcase comes from cloning the constructor into
complete and base variants.  When we clone the body the first time,
walk_tree_1 calls copy_tree_body_r on the type of the artificial TYPE_DECL
we made for the VLA type without calling it on the decl itself, so we
overwrite the type of the TYPE_DECL without copying the decl first.

This has been broken since we started inserting a TYPE_DECL for anonymous
VLAs in r7-457.

This patch fixes walk_tree_1 to call the function on the TYPE_DECL, as we do
for other decls of a DECL_EXPR.

gcc/ChangeLog:

	PR c++/95552
	* tree.c (walk_tree_1): Call func on the TYPE_DECL of a DECL_EXPR.

gcc/testsuite/ChangeLog:

	PR c++/95552
	* g++.dg/ext/vla23.C: New test.