The alias template wasn't working because it applied iter_reference_t to
the pack of iterators before and after passing the pack to the
__indeirect_result helper.

	* include/bits/iterator_concepts.h (indirect_result_t): Do not apply
	iter_reference_t to parameter pack.
	* testsuite/24_iterators/indirect_callable/projected.cc: New test.

From-SVN: r279170