streambuf_iterator.h (istreambuf_iterator<>): Declare std::advance for istreambuf_iterator of char types to be friend.

2017-11-20  François Dumont  <fdumont@gcc.gnu.org>

	* include/bits/streambuf_iterator.h (istreambuf_iterator<>): Declare
	std::advance for istreambuf_iterator of char types to be friend.
	(std::advance(istreambuf_iterator&, _Distance)): New overload.
	* include/std/streambuf (basic_streambuf<>): Declare std::advance for
	istreambuf_iterator of char types to be friend.
	* testsuite/22_locale/money_get/get/char/9.cc: Have
	istreambuf_iterator created on the fly when calling money_get<>::get.
	* testsuite/22_locale/money_get/get/wchar_t/9.cc: Likewise.
	* testsuite/24_iterators/istreambuf_iterator/debug/1_neg.cc: New.
	* testsuite/24_iterators/istreambuf_iterator/debug/2_neg.cc: New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/char/1.cc: New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/char/1_neg.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/char/2.cc: New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/char/2_neg.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/char/3_neg.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/wchar_t/1.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/wchar_t/1_neg.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/wchar_t/2.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/wchar_t/2_neg.cc:
	New.
	* testsuite/25_algorithms/advance/istreambuf_iterators/wchar_t/3_neg.cc:
	New.
	* testsuite/25_algorithms/find/istreambuf_iterators/char/2.cc: Leverage
	on std::advance overload.
	* testsuite/25_algorithms/find/istreambuf_iterators/wchar_t/2.cc:
	Likewise.

From-SVN: r254972