Debug info: Explicitly set the DIVariable::isIndirect() flag for VLAs.
This allows us to get rid of an ugly hack in the backend.
Paired commit with LLVM.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@190960 91177308-0d34-0410-b5e6-96231b3b80d8