* c-decl.c (struct c_binding): Remove contour field; add
	depth, invisible, nested fields.
	(B_IN_SCOPE, B_IN_CURRENT_SCOPE, B_IN_FILE_SCOPE)
	(B_IN_EXTERNAL_SCOPE): New convenience macros.
	(bind): Add invisible and nested arguments. Initialize
	new fields of struct c_binding; adjust loop scanning for
	insertion point.
	(free_binding_and_advance): Clear structure with memset.
	(pop_scope): Adjust to match.  Set DECL_CONTEXT on everything
	in file scope, even if it's in external scope too.
	(pushdecl): Adjust to match.  Create invisible file-scope
	declarations for block-scope forward declarations of static functions.
	(pushtag, warn_if_shadowing, pushdecl_top_level, implicitly_declare)
	(undeclared_variable, lookup_label, declare_label, define_label)
	(lookup_tag, lookup_name, lookup_name_in_scope, builtin_function)
	(c_make_fname_decl, store_parm_decls_newstyle, identifier_global_value)
	(store_parm_decls_oldstyle): Adjust to match.
	(diagnose_mismatched_decls): Correct handling of linkage clashes.
	(merge_decls): No need to copy C_DECL_IN_EXTERNAL_SCOPE.

	* c-tree.h (C_DECL_IN_EXTERNAL_SCOPE): Delete.
	(C_DECL_DECLARED_BUILTIN, C_DECL_REGISTER): Slide down one.

From-SVN: r84046