Remove now redundant code that ensured debug info for class definitions was...

Remove now redundant code that ensured debug info for class definitions was emitted under certain circumstances

Introduced in r181561 - it may've been subsumed by work done to allow
emission of declarations for vtable types while still emitting some of
their member functions correctly for those declarations. Whatever the
reason, the tests pass without this code now.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@292439 91177308-0d34-0410-b5e6-96231b3b80d8