[modules] Turn off a broken optimization: we need to pick up implicit special
members from all redefinitions of a class that have them, in case the special
member is defined in one module but only declared in another.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215675 91177308-0d34-0410-b5e6-96231b3b80d8