re PR c/61854 (Warning single-line comment for -std=c89?)

	PR c/61854
libcpp/
	* init.c (struct lang_flags): Remove cplusplus_comments.
	(cpp_set_lang): Likewise.
	(post_options): Likewise.
	* lex.c (_cpp_lex_direct): Disallow C++ style comments in C90/C94.
testsuite/
	* gcc.dg/cpp/pr61854-1.c: New test.
	* gcc.dg/cpp/pr61854-2.c: New test.
	* gcc.dg/cpp/pr61854-3.c: New test.
	* gcc.dg/cpp/pr61854-3.h: New test.
	* gcc.dg/cpp/pr61854-4.c: New test.
	* gcc.dg/cpp/pr61854-5.c: New test.
	* gcc.dg/cpp/pr61854-6.c: New test.
	* gcc.dg/cpp/pr61854-7.c: New test.
	* gcc.dg/cpp/pr61854-c90.c: New test.
	* gcc.dg/cpp/pr61854-c94.c: New test.

From-SVN: r215339