DebugInfo: Delete subclasses of DIScope

Delete subclasses of (the already defunct) `DIScope`, updating users to
use the raw pointers from the `Metadata` hierarchy directly.

llvm-svn: 235356
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
index 276e7df..a8f17c6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
@@ -191,7 +191,7 @@
 
   StringRef GVName = GV->getName();
   StringRef FuncName;
-  if (DISubprogram SP = getDISubprogram(GV))
+  if (auto *SP = getDISubprogram(GV))
     FuncName = SP->getDisplayName();
 
   // FIXME Clang currently sets DisplayName to "bar" for a C++