* cpphash.h (struct lexer_state): Remove line_extension member.
	* cpplib.c (dequote_string, do_linemarker): New functions.
	(linemarker_dir): New data object.
	(DIRECTIVE_TABLE): No longer need to interpret #line in
	preprocessed source.  Delete obsolete comment about return
	values of handlers.
	(end_directive, directive_diagnostics, _cpp_handle_directive):
	Don't muck with line_extension.
	(directive_diagnostics): No need to issue warnings for
	linemarkers here.
	(_cpp_handle_directive): Issue warnings for linemarkers here,
	when appropriate.  Dispatch linemarkers to do_linemarker, not
	do_line.
	(do_line): Code to handle linemarkers split out to do_linemarker.
	Convert escape sequences in filename argument, both places.

	* cppmacro.c (quote_string): Rename cpp_quote_string and
	export.  All callers changed.
	* cpplib.h (cpp_quote_string): Prototype.
	* cppmain.c (print_line): Call cpp_quote_string on to_file
	before printing it.

	* doc/cpp.texi: Document that escapes are now interpreted in
	#line and in linemarkers, and that non-printing characters are
	converted to octal escapes when linemarkers are generated.

From-SVN: r50780