benchmarks: Add gem_syslatency

Instead of measuring the wakeup latency of a GEM client, we turn the
tables here and ask what is the wakeup latency of a normal process
competing with GEM. In particular, a realtime process that expects
deterministic latency.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/benchmarks/Makefile.sources b/benchmarks/Makefile.sources
index 922b697..81607a5 100644
--- a/benchmarks/Makefile.sources
+++ b/benchmarks/Makefile.sources
@@ -15,6 +15,7 @@
 	gem_mmap			\
 	gem_prw				\
 	gem_set_domain			\
+	gem_syslatency			\
 	gem_userptr_benchmark		\
 	kms_vblank			\
 	$(NULL)