wined3d: Properly handle negative loop step in shader_glsl_loop().
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index d791092..0e01b09 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -725,6 +725,13 @@
     UINT usage_idx;
 };
 
+struct wined3d_shader_loop_control
+{
+    unsigned int count;
+    unsigned int start;
+    int step;
+};
+
 struct wined3d_shader_frontend
 {
     void *(*shader_init)(const DWORD *ptr, const struct wined3d_shader_signature *output_signature);