benchmarks/gem_busy: Exercise the busy ioctl

And include poll(dmabuf) for comparison.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/benchmarks/Makefile.sources b/benchmarks/Makefile.sources
index 00d84ae..f69d4f1 100644
--- a/benchmarks/Makefile.sources
+++ b/benchmarks/Makefile.sources
@@ -2,6 +2,7 @@
 
 benchmarks_prog_list =			\
 	gem_blt				\
+	gem_busy			\
 	gem_create			\
 	gem_exec_ctx			\
 	gem_exec_fault			\