re PR c++/17964 (cpp error messages contain wrong line in C++)

gcc:
	PR c++/17964
	* diagnostic.c (diagnostic_set_info_translated): New function.
	(diagnostic_set_info): Use it.  Add comment.
	* diagnostic.h (diagnostic_set_info_translated): Declare.

gcc/cp:
	* error.c (cp_cpp_error): New function.
	* cp-tree.h (cp_cpp_error): Declare.
	* parser.c (cp_lexer_new_main): Set CPP option client_diagnostic
	and error callback after lexing.

gcc/testsuite:
	* g++.dg/cpp/string-1.C: New test.

libcpp:
	* include/cpplib.h (struct cpp_options): Add client_diagnostic.
	(struct cpp_callbacks): Add error.
	* errors.c (cpp_error): If client_diagnostic, use error callback.
	* charset.c (convert_escape): Don't use %03o in diagnostic.

From-SVN: r106454