re PR middle-end/18785 (isdigit builtin function fails with EBCDIC character sets)

	PR 18785
libcpp:
	* charset.c (LAST_POSSIBLY_BASIC_SOURCE_CHAR): New helper macro.
	(cpp_host_to_exec_charset): New function.
	* include/cpplib.h: Declare cpp_host_to_exec_charset.

gcc:
	* langhooks.h (struct lang_hooks): Add to_target_charset.
	* langhooks.c (lhd_to_target_charset): New function.
	* langhooks-def.h: Declare lhd_to_target_charset.
	(LANG_HOOKS_TO_TARGET_CHARSET): New macro.
	(LANG_HOOKS_INITIALIZER): Update.
	* c-common.c (c_common_to_target_charset): New function.
	* c-common.h: Declare it.
	* c-objc-common.h (LANG_HOOKS_TO_TARGET_CHARSET): Set to
	c_common_to_target_charset.

	* defaults.c (TARGET_BELL, TARGET_BS, TARGET_CR, TARGET_DIGIT0)
	(TARGET_ESC, TARGET_FF, TARGET_NEWLINE, TARGET_TAB, TARGET_VT):
	Delete definitions.
	* system.h: Poison them.
	* doc/tm.texi: Don't discuss them.
	* builtins.c (fold_builtin_isdigit): Use lang_hooks.to_target_charset.
	* c-pretty-print.c (pp_c_integer_constant): Don't use pp_c_char.
	(pp_c_char): Do not attempt to generate letter escapes for
	newline, tab, etc.
	* config/arm/arm.c (output_ascii_pseudo_op): Likewise.
	* config/mips/mips.c (mips_output_ascii): Likewise.
gcc/cp:
	* cp-objcp-common.h (LANG_HOOKS_TO_TARGET_CHARSET): Set to
	c_common_to_target_charset.  Delete bogus comment.
gcc/testsuite:
	* gcc.dg/charset/builtin1.c: New test.

From-SVN: r95304