Cleaup of requirements for optional. While researching LWG3196, I realized that optional did not reject 'const in_place_t' like it should. Added a test as well, and a check for arrays (which were already disallowed, but now we get a better error message). Should not affect anyone's code.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@356918 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed