Improve error message in OcclusionBuffer when width is not a power of two.

Source/Urho3D/Graphics/OcclusionBuffer.cpp

@@ -79,7 +79,7 @@ bool OcclusionBuffer::SetSize(int width, int height, bool threaded)
 
     if (!IsPowerOfTwo((unsigned)width))
     {
-        URHO3D_LOGERROR("Width is not a power of two");
+        URHO3D_LOGERRORF("Requested occlusion buffer width %d is not a power of two", width);
         return false;
     }