DebugInfo: Metadata constructs now start with DI*

LLVM r236120 renamed debug info IR constructs to use a `DI` prefix, now
that the `DIDescriptor` hierarchy has been gone for about a week.  This
commit was generated using the rename-md-di-nodes.sh upgrade script
attached to PR23080, followed by running clang-format-diff.py on the
`lib/` portion of the patch.

llvm-svn: 236121
diff --git a/clang/test/CodeGenCXX/debug-info-blocks.cpp b/clang/test/CodeGenCXX/debug-info-blocks.cpp
index 608a273..7762726 100644
--- a/clang/test/CodeGenCXX/debug-info-blocks.cpp
+++ b/clang/test/CodeGenCXX/debug-info-blocks.cpp
@@ -10,9 +10,9 @@
   __block A a;
 }
 
-// CHECK: !MDSubprogram(name: "__Block_byref_object_copy_",
+// CHECK: !DISubprogram(name: "__Block_byref_object_copy_",
 // CHECK-SAME:          line: 10,
 // CHECK-SAME:          isLocal: true, isDefinition: true
-// CHECK: !MDSubprogram(name: "__Block_byref_object_dispose_",
+// CHECK: !DISubprogram(name: "__Block_byref_object_dispose_",
 // CHECK-SAME:          line: 10,
 // CHECK-SAME:          isLocal: true, isDefinition: true