Debug Info: In DIBuilder, the context field of a DICompositeType is updated
to use DIScopeRef.

A paired commit at clang is required due to changes to DIBuilder.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192256 91177308-0d34-0410-b5e6-96231b3b80d8