PR c++/26068
	* parser.c (cp_parser_set_storage_class): Check for 
	invalid uses of storage classes on unbraced linkage
	specifications.
	(cp_parser_decl_specifier_seq): Pass keywords, not storage classes,
	to cp_parser_set_storage_class.
	PR c++/26068
	* g++.dg/opt/pr17697-3.C: Remove invalid extern specifier.
	* g++.dg/parse/linkage1.C: New test.

From-SVN: r113869