The change approved in Belfast did not actually rename the concept from
std::default_constructible to std::default_initializable, even though
that was intended. That is expected to be done soon as a separate issue,
so I'm implementing that now too.
* include/bits/iterator_concepts.h (weakly_incrementable): Adjust.
* include/std/concepts (default_constructible): Rename to
default_initializable and require default-list-initialization and
default-initialization to be valid (LWG 3149).
(semiregular): Adjust to new name.
* testsuite/std/concepts/concepts.lang/concept.defaultconstructible/
1.cc: Rename directory to concept.defaultinitializable and adjust to
new name.
* testsuite/std/concepts/concepts.lang/concept.defaultinitializable/
lwg3149.cc: New test.
* testsuite/util/testsuite_iterators.h (test_range): Adjust.
From-SVN: r278314
