[Bug target/81266] New: FAIL: 30_threads/thread/native_handle/typesizes.cc execution test on darwin

["dominiq at lps dot ens.fr" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81266

            Bug ID: 81266
           Summary: FAIL: 30_threads/thread/native_handle/typesizes.cc
                    execution test on darwin
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dominiq at lps dot ens.fr
                CC: iains at gcc dot gnu.org, redi at gcc dot gnu.org, ro at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-apple-darwin16
            Target: x86_64-apple-darwin16
             Build: x86_64-apple-darwin16

After revision r249217 the test 30_threads/thread/native_handle/typesizes.cc
fails at run time on darwin with (it was UNSUPPORTED before this revision)

terminate called after throwing an instance of 'std::runtime_error'
  what():
size of _Tp: 4
alignment of _Tp: 4
size of *(_Tp::native_handle_type): 4096
alignment of *(_Tp::native_handle_type): 4096