Fixed issue int RnederManager.proeloadScene that was causing failure when attempting to load CPU usage buffers to the GPU

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@10018 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/renderer/RenderManager.java

@@ -596,7 +596,7 @@ public class RenderManager {
             Mesh mesh = gm.getMesh();
             if (mesh != null) {
                 for (VertexBuffer vb : mesh.getBufferList().getArray()) {
-                    if (vb.getData() != null) {
+                    if (vb.getData() != null && vb.getUsage() != VertexBuffer.Usage.CpuOnly) {
                         renderer.updateBufferData(vb);
                     }
                 }