lex.c (parse_strconst_pragma): Return error_mark_node instead of "(tree)-1" to indica...

lex.c (parse_strconst_pragma): Return error_mark_node instead of "(tree)-1" to indicate failure.

	* lex.c (parse_strconst_pragma): Return error_mark_node instead of
	"(tree)-1" to indicate failure.  Simplify.
	(handle_pragma_interface): Test for error_mark_node instead of
	"(tree)-1".
	(handle_pragma_implementation): Likewise.

From-SVN: r110932