autotools requires headers to be listed

Too used to kbuild where you only specify objects.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/benchmarks/Makefile.sources b/benchmarks/Makefile.sources
index 3a94115..ec3bdc5 100644
--- a/benchmarks/Makefile.sources
+++ b/benchmarks/Makefile.sources
@@ -1,6 +1,8 @@
 benchmarksdir=$(libexecdir)/intel-gpu-tools/benchmarks
 
 benchmarks_prog_list =			\
+	ewma.h				\
+	ilog2.h				\
 	gem_blt				\
 	gem_busy			\
 	gem_create			\