swrast: add missing texfetch table entry for MESA_FORMAT_ARGB2101010_UINT

As with the other integer-valued formats, use NULL until we support
integer textures.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=43316

Tested-by: Vinson Lee <vlee@vmware.com>
Signed-off-by: Brian Paul <brianp@vmware.com>

src/mesa/swrast/s_texfetch.c

@@ -1260,6 +1260,13 @@ texfetch_funcs[MESA_FORMAT_COUNT] =
       fetch_texel_2d_z32f_x24s8,
       fetch_texel_3d_z32f_x24s8,
       store_texel_z32f_x24s8
+   },
+   {
+      MESA_FORMAT_ARGB2101010_UINT,
+      NULL,
+      NULL,
+      NULL,
+      NULL
    }
 };