In the verify-only pass, check that items that don't have an initializer in an init...

In the verify-only pass, check that items that don't have an initializer in an init list can be value-initialized, at least when designated initializers are not involved. No test case yet, since early failures cannot be distinguished from late failures until overload resolution works.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@142146 91177308-0d34-0410-b5e6-96231b3b80d8