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-union-template.cpp b/clang/test/CodeGenCXX/debug-info-union-template.cpp
index 009ab04..0616d72 100644
--- a/clang/test/CodeGenCXX/debug-info-union-template.cpp
+++ b/clang/test/CodeGenCXX/debug-info-union-template.cpp
@@ -10,8 +10,8 @@
   Value<float> f;
 }
 
-// CHECK: !MDCompositeType(tag: DW_TAG_union_type, name: "Value<float>",
+// CHECK: !DICompositeType(tag: DW_TAG_union_type, name: "Value<float>",
 // CHECK-SAME:             templateParams: [[TTPARAM:![0-9]+]]
 // CHECK-SAME:             identifier: "_ZTSN7PR156375ValueIfEE"
 // CHECK: [[TTPARAM]] = !{[[PARAMS:.*]]}
-// CHECK: [[PARAMS]] = !MDTemplateTypeParameter(name: "T"
+// CHECK: [[PARAMS]] = !DITemplateTypeParameter(name: "T"