mesa: reorder gl_image_unit

reduces 40->32
but reduces use in context from 7680->6144.

Acked-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Alex Deucher alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/mesa/main/mtypes.h

@@ -4166,6 +4166,13 @@ struct gl_image_unit
     */
    GLboolean Layered;
 
+   /**
+    * GL_TRUE if the state of this image unit is valid and access from
+    * the shader is allowed.  Otherwise loads from this unit should
+    * return zero and stores should have no effect.
+    */
+   GLboolean _Valid;
+
    /**
     * Layer of the texture object bound to this unit, or zero if the
     * whole level is bound.
@@ -4190,12 +4197,6 @@ struct gl_image_unit
     */
    mesa_format _ActualFormat;
 
-   /**
-    * GL_TRUE if the state of this image unit is valid and access from
-    * the shader is allowed.  Otherwise loads from this unit should
-    * return zero and stores should have no effect.
-    */
-   GLboolean _Valid;
 };
 
 /**