DebugInfo: Remove DITypedArray<>, replace with typedefs

Replace all uses of `DITypedArray<>` with `MDTupleTypedArrayWrapper<>`
and `MDTypeRefArray`.  The APIs are completely different, but the
provided functionality is the same: treat an `MDTuple` as if it's an
array of a particular element type.

To simplify this patch a bit, I've temporarily typedef'ed
`DebugNodeArray` to `DIArray` and `MDTypeRefArray` to `DITypeArray`.
I've also temporarily conditionalized the accessors to check for null --
eventually these should be changed to asserts and the callers should
check for null themselves.

There's a tiny accompanying patch to clang.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234290 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/Transforms/Utils/Cloning.cpp

@@ -323,8 +323,8 @@ TEST_F(CloneFunc, SubprogramInRightCU) {
   DICompileUnit CU1 = cast<MDCompileUnit>(*Iter);
   Iter++;
   DICompileUnit CU2 = cast<MDCompileUnit>(*Iter);
-  EXPECT_TRUE(CU1.getSubprograms().getNumElements() == 0
-           || CU2.getSubprograms().getNumElements() == 0);
+  EXPECT_TRUE(CU1.getSubprograms().size() == 0 ||
+              CU2.getSubprograms().size() == 0);
 }
 
 // Test that instructions in the old function still belong to it in the