Allow 4 as a valid debug info version.

llvm-svn: 187763
diff --git a/llvm/lib/DebugInfo/DWARFContext.h b/llvm/lib/DebugInfo/DWARFContext.h
index af9965f..058476e 100644
--- a/llvm/lib/DebugInfo/DWARFContext.h
+++ b/llvm/lib/DebugInfo/DWARFContext.h
@@ -130,7 +130,7 @@
   virtual const RelocAddrMap &infoDWORelocMap() const = 0;
 
   static bool isSupportedVersion(unsigned version) {
-    return version == 2 || version == 3;
+    return version == 2 || version == 3 || version == 4;
   }
 private:
   /// Return the compile unit that includes an offset (relative to .debug_info).