re PR libstdc++/51649 (pretty printers don't handle std::__7:: namespace)

re PR libstdc++/51649 (pretty printers don't handle std::__7:: namespace)

	PR libstdc++/51649:
	* testsuite/libstdc++-prettyprinters/debug.cc: New file.
	* testsuite/lib/gdb-test.exp (regexp-test): New proc.
	(note-test): Update.
	(gdb-test): Handle regexp tests.  Add some logging.
	* testsuite/libstdc++-prettyprinters/simple.cc: Compile with -O0.
	(placeholder, use): Remove.
	(main): Add tests for deque, list, map, and set iterators.  Add
	tests for slist and slist iterator.
	* testsuite/libstdc++-prettyprinters/48362.cc (main): Handle __7
	namespace.
	* python/libstdcxx/v6/printers.py (StdListPrinter.children): Use
	the type's _Node typedef.
	(StdListIteratorPrinter.to_string): Change how node type is
	computed.
	(StdSlistPrinter.children): Use the type's _Node typedef.
	(StdSlistIteratorPrinter.to_string): Likewise.
	(StdRbtreeIteratorPrinter.to_string): Use the type's _Link_type
	typedef.
	(StdMapPrinter.children): Change how the node's type is computed.
	(StdSetPrinter.children): Likewise.
	(StdForwardListPrinter.children): Use the type's _Node typedef.
	(Printer.add_version): New method.
	(Printer.add_container): New method.
	(build_libstdcxx_dictionary): Handle __7 and __cxx1998
	namespaces.
	(find_type): New function.

From-SVN: r183732