DebugIRTests: Fixup for r204130.

llvm-svn: 204132
diff --git a/llvm/unittests/Transforms/DebugIR/DebugIR.cpp b/llvm/unittests/Transforms/DebugIR/DebugIR.cpp
index 497dae3..9b89c15 100644
--- a/llvm/unittests/Transforms/DebugIR/DebugIR.cpp
+++ b/llvm/unittests/Transforms/DebugIR/DebugIR.cpp
@@ -278,7 +278,7 @@
   // verify DebugIR did not generate a file
   ASSERT_FALSE(removeIfExists(Path)) << "Unexpected file " << Path;
 
-  DICompileUnit CU(*Finder.compile_unit_begin());
+  DICompileUnit CU(*Finder.compile_units().begin());
 
   // Verify original CU information is retained
   ASSERT_EQ(Filename, CU.getFilename());