brw: add serialize send stats

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Sagar Ghuge <sagar.ghuge@intel.com>
Reviewed-by: Alyssa Anne Rosenzweig <alyssa.rosenzweig@intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37394>

src/util/shader_stats.xml

@@ -133,6 +133,11 @@
             Number of instructions in the final generated shader executable
             which access external units such as the constant cache or the sampler.
          </stat>
+         <stat name="Serialized SEND Count" display="Serialized send messages">
+            Number of instructions in the final generated shader
+            executable which access external units such as the
+            constant cache or the sampler in a serialized way.
+         </stat>
          <stat name="Loop Count" display="Loop count">
             Number of loops (not unrolled) in the final generated shader
             executable.