c-lex.c (c_lex_with_flags): For CPP_COMMENT token with PREV_FALLTHROUGH...

c-lex.c (c_lex_with_flags): For CPP_COMMENT token with PREV_FALLTHROUGH...

	* c-lex.c (c_lex_with_flags) <case CPP_COMMENT>: For CPP_COMMENT
	token with PREV_FALLTHROUGH, skip all following CPP_PADDING and
	CPP_COMMENT tokens and set add_flags to PREV_FALLTHROUGH afterwards.

	* doc/invoke.texi (-Wimplicit-fallthrough): Document the accepted
	FALLTHRU comment styles.

	* lex.c (fallthrough_comment_p): Fix off-by-one size comparison
	errors, cleanup.
	(_cpp_lex_direct): Allow arbitrary comments in between
	fallthrough_comment_p comment and following token.

	* c-c++-common/Wimplicit-fallthrough-23.c: New test.
	* c-c++-common/Wimplicit-fallthrough-24.c: New test.

From-SVN: r240884