updated for version 7.4.398

Problem:    Gcc error for the argument of InterlockedIncrement() and
            InterlockedDecrement(). (Axel Bender)
Solution:   Remove "unsigned" from the cRefCount_ declaration.

src/gui_dwrite.cpp

@@ -377,7 +377,7 @@ public:
     }
 
 private:
-    unsigned long cRefCount_;
+    long cRefCount_;
     IDWriteBitmapRenderTarget* pRenderTarget_;
     IDWriteRenderingParams* pRenderingParams_;
 };