fix build

Windows seems to be unhappy about bpixel.cxx removal.
This partially reverts 3abfdd08.

Change-Id: I3a27bafa9ead14ba19d0f00a6be086df6c468e19

basegfx/Library_basegfx.mk

@@ -45,6 +45,7 @@ $(eval $(call gb_Library_add_exception_objects,basegfx,\
     basegfx/source/matrix/b2dhommatrixtools \
     basegfx/source/matrix/b3dhommatrix \
     basegfx/source/numeric/ftools \
+    basegfx/source/pixel/bpixel \
     basegfx/source/point/b2dpoint \
     basegfx/source/point/b2ipoint \
     basegfx/source/point/b3dpoint \

basegfx/inc/basegfx/pixel/bpixel.hxx

@@ -125,6 +125,9 @@ namespace basegfx
         {
             return (rPixel.maPixelUnion.maCombinedRGBO.mnValue != maPixelUnion.maCombinedRGBO.mnValue);
         }
+
+        // empty element
+        static const BPixel& getEmptyBPixel();
     };
 
     //////////////////////////////////////////////////////////////////////////

basegfx/source/pixel/bpixel.cxx

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed
+ * with this work for additional information regarding copyright
+ * ownership. The ASF licenses this file to you under the Apache
+ * License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <basegfx/pixel/bpixel.hxx>
+#include <rtl/instance.hxx>
+
+namespace { struct EmptyBPixel : public rtl::Static<basegfx::BPixel, EmptyBPixel> {}; }
+
+//////////////////////////////////////////////////////////////////////////////
+
+namespace basegfx
+{
+    const BPixel& BPixel::getEmptyBPixel()
+    {
+        return EmptyBPixel::get();
+    }
+
+    //////////////////////////////////////////////////////////////////////////
+    // external operators
+
+} // end of namespace basegfx
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */