DebugInfo: Remove DIDescriptor from the DebugInfo API

Stop using `DIDescriptor` and its subclasses in the `DebugInfoFinder`
API, as well as the rest of the API hanging around in `DebugInfo.h`.

llvm-svn: 235240
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index 56975ea..917a163 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -89,7 +89,7 @@
     bool doInitialization(CallGraph &CG) override;
     /// The maximum number of elements to expand, or 0 for unlimited.
     unsigned maxElements;
-    DenseMap<const Function *, DISubprogram> FunctionDIs;
+    DenseMap<const Function *, MDSubprogram *> FunctionDIs;
   };
 }