mesa: move ElementArrayBufferObj to gl_array_object

According opengl spec 4.2.pdf table 6.12 (Vertex Array Object State) at
page 515, the element buffer object is listed in vertex array object.

So, move the ElementArrayBufferObj inside gl_array_object to make
element buffer object per-vao.

This would fix most of(3 left) intel oglc vao test fail

NOTE: this is a candidate for the 7.11 branch.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/main/arrayobj.c

@@ -133,6 +133,7 @@ _mesa_delete_array_object( struct gl_context *ctx, struct gl_array_object *obj )
 {
    (void) ctx;
    unbind_array_object_vbos(ctx, obj);
+   _mesa_reference_buffer_object(ctx, &obj->ElementArrayBufferObj, NULL);
    _glthread_DESTROY_MUTEX(obj->Mutex);
    free(obj);
 }
@@ -252,6 +253,9 @@ _mesa_initialize_array_object( struct gl_context *ctx,
 #if FEATURE_point_size_array
    init_array(ctx, &obj->PointSize, 1, GL_FLOAT);
 #endif
+
+   _mesa_reference_buffer_object(ctx, &obj->ElementArrayBufferObj,
+                                 ctx->Shared->NullBufferObj);
 }