re PR c++/45330 (Suggest likely nested-name-specifiers for undeclared identifiers.)

gcc/
	PR c++/45330
	* params.def (CXX_MAX_NAMESPACES_FOR_DIAGNOSTIC_HELP): New parameter.
	* doc/invoke.texi (cxx-max-namespaces-for-diagnostic-help): Document.

gcc/cp/
	PR c++/45330
	* cp-tree.h (suggest_alternatives_for, location_of): Declare.
	* error.c (dump_expr): Handle TYPE_DECL.
	(location_of): Unstaticize.
	* name-lookup.c (suggest_alternatives_for): New function.
	* lex.c (unqualified_name_lookup_error): Call it.

gcc/testsuite/
	PR c++/45330
	* g++.dg/pr45330.C: New test.
	* g++.dg/ext/builtin3.C: Adjust.
	* g++.dg/lookup/error1.C: Adjust.
	* g++.dg/lookup/koenig5.C: Adjust.
	* g++.dg/overload/koenig1.C: Adjust.
	* g++.dg/parse/decl-specifier-1.C: Adjust.
	* g++.dg/template/static10.C: Adjust.
	* g++.old-deja/g++.mike/ns5.C: Adjust.
	* g++.old-deja/g++.mike/ns7.C: Adjust.
	* g++.old-deja/g++.ns/koenig5.C: Adjust.
	* g++.old-deja/g++.ns/koenig9.C: Adjust.
	* g++.old-deja/g++.other/lineno5.C: Adjust.

From-SVN: r167536