c-common.c (handle_visibility_attribute): Set DECL_VISIBILITY field instead of hangin...

c-common.c (handle_visibility_attribute): Set DECL_VISIBILITY field instead of hanging an attribute object off the decl.

	* c-common.c (handle_visibility_attribute): Set DECL_VISIBILITY
	field instead of hanging an attribute object off the decl.
	* tree.h (DECL_VISIBLITY): New accessor macro for
	symbol_visibility field in struct tree_decl.
	(enum symbol_visibility): Move definition to before tree_decl.
	(struct tree_decl): Define new two-bit field, symbol_visibility.
	(decl_visibility): Remove declaration.
	* varasm.c (maybe_assemble_visibility): Use DECL_VISIBILITY
	instead of decl_visibility.
	(default_binds_local_p_1):  Use DECL_VISIBILITY	instead of
	decl_visibility.
	(decl_visibility): Remove.
	* cp/decl.c (duplicate_decls): copy DECL_VISIBILITY field.
	* cp/method.c (use_thunk): give thunk same visibility as function.
	* cp/optimize.c (maybe_clone_body): copy DECL_VISIBILITY field.

From-SVN: r73320