Prevent Y-offset from exceeding valid range in texture upload code. This

fixes bugzilla #960.

src/mesa/drivers/dri/r200/r200_texmem.c

@@ -382,6 +382,14 @@ static void uploadSubImage( r200ContextPtr rmesa, r200TexObjPtr t,
    /* copy (x,y,width,height,data) */
    memcpy( &tmp, &t->image[face][hwlevel], sizeof(tmp) );
 
+   /* Adjust the base offset to account for the Y-offset.  This is done,
+    * instead of just letting the Y-offset automatically take care of it,
+    * because it is possible, for very large textures, for the Y-offset
+    * to exceede the [-8192,+8191] range.
+    */
+   tex.offset += tmp.y * 1024;
+   tmp.y = 0;
+    
    LOCK_HARDWARE( rmesa );
    do {
       ret = drmCommandWriteRead( rmesa->dri.fd, DRM_RADEON_TEXTURE,