* cp/parser.c (struct cp_token): new one-bit field , implicit_extern_c
(cp_lexer_get_preprocessor_token): Set implicit_extern_c for
tokens that come from headers that are implicitly extern "C".
(struct cp_parser): new one-bit field, implicit_extern_c.
(cp_parser_new): Set parser's implicit_extern_c to false.
(cp_parser_translation_unit): Pop lang context if we were in a
header that was implicitly extern "C".
(cp_parser_declaration_seq_opt): Push/pop lang context as
required by the token's and parser's implicit_extern_c.
From-SVN: r88203
