Remove some more using-declarations from namespace __gnu_cxx

Remove some more using-declarations from namespace __gnu_cxx

Similar to some recent patches, this removes using-declarations for
names from namespace std, so that they are not redeclared in __gnu_cxx.

	* include/bits/stl_iterator.h (namespace __gnu_cxx): Remove
	using-declarations for std::iterator and std::iterator_traits.
	(__gnu_cxx::__normal_iterator): Qualify iterator_traits.
	* include/ext/algorithm (namespace __gnu_cxx): Remove
	using-declarations for std names and qualify those names when used.
	Also refer to std::min in parentheses to protect against function-like
	macros.
	* include/ext/rc_string_base.h: Qualify iterator_traits.
	* include/ext/sso_string_base.h: Qualify iterator_traits.

From-SVN: r277630