* cpphash.h (struct spec_nodes): Remove n__CHAR_UNSIGNED__.
	* cpphash.c (_cpp_init_hashtable): Similarly.
	* cppinit.c (cpp_create_reader): Default the signed_char flag.
	(init_builtins): Define __CHAR_UNSIGNED__ appropriately.
	(COMMAND_LINE_OPTIONS): Recognise -f{un,}signed-char.
	(cpp_handle_option): Handle the new options.
	* cpplex.c (cpp_interpret_charconst): Use new flag.
	* cpplib.h (struct cpp_options): New member signed_char.
	* gcc.c (cpp_unique_options): Remove %c spec and documentation.
	(cpp_options): Handle -fsigned-char and -funsigned-char.
	(static_specs): Remove signed_char_spec.
	(do_spec1): Don't handle %c.
	* system.h: Poison SIGNED_CHAR_SPEC.
	* tradcif.y (yylex): Use flag_signed_char.
	* tradcpp.h (flag_signed_char): New.
	* tradcpp.c (flag_signed_char): New.
	(main): Handle new command-line options.
	(initialize_builtins): Define __CHAR_UNSIGNED__ if appropriate.
config:
	* alpha/alpha.h (SIGNED_CHAR_SPEC): Remove.
	* avr/avr.h: Remove old comments.
	* i960/i960.h (CPP_SPEC): Pass -fsigned-char if -mic*.
	(CC1_SPEC): Pass -fsigned-char if -mic*.
	(SIGNED_CHAR_SPEC): Remove.
doc:
	* tm.texi (SIGNED_CHAR_SPEC): Remove documentation.
testsuite:
	* gcc.dg/cpp/uchar-1.c, uchar-2.c, uchar-3.c: New tests.

From-SVN: r49444