Do defaulted constructors properly.

Explictly defaultedness is correctly reflected on the AST, but there are
no changes to how that affects the definition of functions or much else
really.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130974 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed