* cppinit.c (cpp_reader_init): Initialise col_adjust and
	default tab stop size.
	(no_num, OPT_ftabstop): New.
	(handle_option): Handle "ftabstop=" command-line option.
	(print_help): Document it.
	* cpplex.c (COLUMN): Remove.
	(handle_newline): Reset col_adjust.
	(skip_whitespace): Update col_adjust as tabs encountered.
	(_cpp_lex_line): Update to use col_adjust.  Call
	skip_whitespace for all whitespace.
	* cpplib.h (struct cpp_options): New member tabstop.
	(struct cpp_reader): New member col_adjust.
	(CPP_BUF_COL): Update.
	(CPP_BUF_COLUMN): New.
	* cpp.texi: Document "-ftabstop=" command line option.

From-SVN: r33982