2017-04-20  Edward Smith-Rowland  <3dw4rd@verizon.net>

	PR libstdc++/68397 std::tr1::expint fails ... long double arguments.
	* include/tr1/exp_integral.tcc: Increase iteration limits.
	* testsuite/tr1/5_numerical_facilities/special_functions/15_expint/
	pr68397.cc: New test.
	* testsuite/special_functions/14_expint/pr68397.cc: New test.