frontend/dri: remove __DRIdrawableRec::dri2::stamp

It's practically unused. It was only off by one at initialization, but
that didn't have any effect.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19741>

src/gallium/frontends/dri/dri2.c

@@ -103,8 +103,7 @@ dri2_invalidate_drawable(__DRIdrawable *dPriv)
 {
    struct dri_drawable *drawable = dri_drawable(dPriv);
 
-   dPriv->dri2.stamp++;
-   drawable->dPriv->lastStamp = drawable->dPriv->dri2.stamp;
+   drawable->dPriv->lastStamp++;
    drawable->texture_mask = 0; /* mark all attachments as invalid */
 
    p_atomic_inc(&drawable->base.stamp);

src/gallium/frontends/dri/dri_drawable.c

@@ -66,11 +66,6 @@ dri_st_framebuffer_validate(struct st_context_iface *stctx,
    /* record newly allocated textures */
    new_mask = (statt_mask & ~drawable->texture_mask);
 
-   /*
-    * dPriv->dri2.stamp is the server stamp.  dPriv->lastStamp is the
-    * client stamp.  It has the value of the server stamp when last
-    * checked.
-    */
    do {
       lastStamp = drawable->dPriv->lastStamp;
       new_stamp = (drawable->texture_stamp != lastStamp);

src/gallium/frontends/dri/dri_util.c

@@ -850,8 +850,6 @@ driCreateNewDrawable(__DRIscreen *screen,
        return NULL;
     }
 
-    pdraw->dri2.stamp = pdraw->lastStamp + 1;
-
     return pdraw;
 }
 

src/gallium/frontends/dri/dri_util.h

@@ -296,22 +296,14 @@ struct __DRIdrawableRec {
     int refcount;
 
     /**
-     * Last value of the stamp.
+     * Increased when the loader calls invalidate.
      *
-     * If this differs from the value stored at __DRIdrawable::dri2.stamp,
-     * then the drawable information has been modified by the X server, and the
-     * drawable information (below) should be retrieved from the X server.
+     * If this changes, the drawable information (below) should be retrieved
+     * from the loader.
      */
     unsigned int lastStamp;
 
     int w, h;
-
-    /**
-     * Drawable timestamp.  Increased when the loader calls invalidate.
-     */
-    struct {
-	unsigned int stamp;
-    } dri2;
 };
 
 extern uint32_t

src/gallium/frontends/dri/kopper.c

@@ -993,8 +993,6 @@ kopperCreateNewDrawable(__DRIscreen *screen,
        return NULL;
     }
 
-    pdraw->dri2.stamp = pdraw->lastStamp + 1;
-
     return pdraw;
 }