* langhooks.h (struct lang_hooks_for_tree_inlining): Add
	var_mod_type_p.
	* langhooks-def.h: Default for tree_inlining.var_mod_type_p is
	hook_tree_bool_false.

	* tree.c (variably_modified_type_p): Moved here from
	cp/tree.c.  Use lang_hooks.tree_inlining.var_mod_type_p for
	language-specific cases.  Due to this, must weaken some 'if
	and only if' checks to merely 'if'.
	* tree.h: Prototype variably_modified_type_p.

	* tree-inline.c (walk_tree): #undef WALK_SUBTREE_TAIL at end.

cp:
	* cp-lang.c (cp_var_mod_type_p): New: C++ hook for
	variably_modified_type_p.
	* cp-tree.h: Remove prototype of variably_modified_type_p.
	* tree.c (variably_modified_type_p): Remove; now implemented
	in language-independent code.

From-SVN: r58460