* cpplib.h (cpp_reader): Remove if_stack.  Change
	potential_control_macro to a cpp_hashnode *.  Add skipping flag.
	* cpphash.h (struct ihash): Change control_macro to a
	cpp_hashnode * and shorten name to cmacro.
	Add NEVER_REINCLUDE constant.

	* cppfiles.c (redundant_include_p): Drop cpp_reader argument.
	Examine the cmacro node directly, no need to call cpp_defined.
	(_cpp_execute_include, read_include_file): Set cmacro to
	NEVER_REINCLUDE, not U"".
	* cpplex.c (cpp_push_buffer): Don't set new->if_stack.
	(cpp_get_token): If pfile->skipping is true, discard text and
	keep scanning until we hit a directive; don't expand macros.

	* cpplib.c (struct if_stack): Remove if_succeeded, add
	was_skipping. Change control_macro to a cpp_hashnode * and
	shorten name to cmacro.  Remove typedef IF_STACK.
	(parse_ifdef), detect_if_not_defined): Return a cpp_hashnode *.
	(conditional_skip, skip_if_group,
	consider_directive_while_skipping): Delete.
	(push_conditional): New.
	(_cpp_handle_directive): Don't process directives other than
	conditionals if we are skipping.

	(do_ifdef, do_ifndef, do_if, do_else, do_elif, do_endif):
	Update to new scheme.
	(validate_else): Skip rest of line here, unconditionally.
	(_cpp_unwind_if_stack): The stack is per-buffer.  Force
	pfile->skipping off.

	(all): Remove `scare quotes' from error messages.

	* gcc.dg/cpp-mi.c: Add another case, cpp-mix.h, where the
	guard macro is already defined when the header is first
	included.
	* gcc.dg/cpp-mix.h: New file.
	* gcc.dg/endif-label.c: Update patterns to match compiler.

	* g++.brendan/complex1.C: Declare abort.
	* g++.law/refs4.C: Remove XFAIL.
	* g++.oliva/expr2.C: Declare abort and exit.

From-SVN: r34253