* c-lex.c (lex_string): Let cpp_parse_escape handles truncation
	and sign-extension.
	(lex_charconst): Update for change in prototype of
	cpp_interpret_charconst.  Extend from cppchar_t to HOST_WIDE_INT
	appropriately.
	* cpphash.h (BITS_PER_CPPCHAR_T): New.
	* cppinit.c (cpp_create_reader): Initialize them for no
	change in semantics.
	(cpp_post_options): Add sanity checks.
	* cpplex.c (cpp_parse_escape): Handle precision, sign-extension
	and truncation issues.  Calculate in type cppchar_t.
	(MAX_CHAR_TYPE_SIZE, MAX_WCHAR_TYPE_SIZE): Remove.
	(cpp_interpret_charconst): Calculate in type cppchar_t.  Handle
	run-time dependent precision correctly.  Return whether the
	result is signed or not.
	* cpplib.c (dequote_string): Use cppchar_t; update.
	* cpplib.h (cppchar_signed_t): New.
	struct cpp_options): New precision members.
	(cpp_interpret_charconst, cpp_parse_escape): Update prototypes.

From-SVN: r53152