DebugInfo: Fix for an improvement to DIBuilder to not emit {i32 0} for zero-length arrays.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200722 91177308-0d34-0410-b5e6-96231b3b80d8
Tidy up and reduce some comment redundancy.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200723 91177308-0d34-0410-b5e6-96231b3b80d8