ensure all gapk header files are included in 'dist'
diff --git a/include/gapk/Makefile.am b/include/gapk/Makefile.am
index 19dcc9d..5fcc3b9 100644
--- a/include/gapk/Makefile.am
+++ b/include/gapk/Makefile.am
@@ -1,2 +1,6 @@
-noinst_HEADERS =	codecs.h	\
+noinst_HEADERS =	benchmark.h	\
+			codecs.h	\
+			formats.h	\
+			get_cycles.h	\
+			procqueue.h	\
 			utils.h