DebugInfo: Drop rest of DIDescriptor subclasses

Delete the remaining subclasses of (the already deleted) `DIDescriptor`.
Part of PR23080.

llvm-svn: 235404
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 32adb40..29a163b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -137,7 +137,7 @@
 
 bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
   SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
-  DIVariable DV = Var->getVariable();
+  const MDLocalVariable *DV = Var->getVariable();
   // Variables with positive arg numbers are parameters.
   if (unsigned ArgNum = DV->getArg()) {
     // Keep all parameters in order at the start of the variable list to ensure