NFC: Move API uses of MD5::MD5Result to Optional rather than a pointer.

Differential Revision: https://reviews.llvm.org/D60290

llvm-svn: 357736
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index e6913bc..fbb7a57 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -104,7 +104,7 @@
   // extend .file to support this.
   unsigned CUID = Asm->OutStreamer->hasRawTextSupport() ? 0 : getUniqueID();
   if (!File)
-    return Asm->OutStreamer->EmitDwarfFileDirective(0, "", "", nullptr, None, CUID);
+    return Asm->OutStreamer->EmitDwarfFileDirective(0, "", "", None, None, CUID);
   return Asm->OutStreamer->EmitDwarfFileDirective(
       0, File->getDirectory(), File->getFilename(), getMD5AsBytes(File),
       File->getSource(), CUID);