libstdc++: [_GLIBCXX_INLINE_VERSION] Add gdb pretty print for _GLIBCXX_DEBUG

In _GLIBCXX_DEBUG mode containers are in std::__debug namespace but not template
parameters. In _GLIBCXX_INLINE_VERSION mode most types are in std::__8 namespace but
not std::__debug containers. We need to register specific type printers for this
combination.

libstdc++-v3/ChangeLog:

	* python/libstdcxx/v6/printers.py (add_one_template_type_printer): Register
	printer for types in std::__debug namespace with template parameters in std::__8
	namespace.