Add extra testing for init-captures.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191608 91177308-0d34-0410-b5e6-96231b3b80d8
Add compat/extension warnings for init captures.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191609 91177308-0d34-0410-b5e6-96231b3b80d8