Tested on Linux-x64, running full suite on Linux-ppc64. It seems fitting
to put the test into the library tests, we don't have separate tests
on the front-end side for __is_constructible, so I think adding such
would be a separate job.

2017-05-25  Ville Voutilainen  <ville.voutilainen@gmail.com>

    cp/

    PR c++/80812
    * method.c (constructible_expr): Strip array types before calling
    build_value_init.

    libstdc++/

    PR c++/80812
    * testsuite/20_util/is_constructible/80812.cc: New.