bvh: Fix headless build.

diff --git a/simgear/bvh/BVHLineSegmentVisitor.hxx b/simgear/bvh/BVHLineSegmentVisitor.hxx
index aa681a28c771496de8bb4fd7dbe5675259e8cdc5..87883fb1cd883919c89d13f0708459c65dd574b0 100644 (file)
--- a/simgear/bvh/BVHLineSegmentVisitor.hxx
+++ b/simgear/bvh/BVHLineSegmentVisitor.hxx
@@ -20,13 +20,14 @@
 
 #include <simgear/math/SGGeometry.hxx>
 #include <simgear/structure/SGSharedPtr.hxx>
-#include <simgear/scene/material/mat.hxx>
 
 #include "BVHVisitor.hxx"
 #include "BVHNode.hxx"
 
 namespace simgear {
 
+class BVHMaterial;
+
 class BVHLineSegmentVisitor : public BVHVisitor {
 public:
     BVHLineSegmentVisitor(const SGLineSegmentd& lineSegment,