Fix build error with clang and gcc.

llvm-svn: 304589
diff --git a/llvm/lib/ObjectYAML/CodeViewYAMLDebugSections.cpp b/llvm/lib/ObjectYAML/CodeViewYAMLDebugSections.cpp
index 1d62d1b..a85dcf9 100644
--- a/llvm/lib/ObjectYAML/CodeViewYAMLDebugSections.cpp
+++ b/llvm/lib/ObjectYAML/CodeViewYAMLDebugSections.cpp
@@ -261,7 +261,7 @@
       }
     }
   }
-  return Result;
+  return llvm::cast<DebugSubsection>(std::move(Result));
 }
 
 std::unique_ptr<DebugSubsection>
@@ -282,7 +282,7 @@
       Result->addExtraFile(EF);
     }
   }
-  return Result;
+  return llvm::cast<DebugSubsection>(std::move(Result));
 }
 
 static Expected<SourceFileChecksumEntry>