add missing config.h.in

Change-Id: I7f294d3a0ce1acb961c49a8a9bee0f3e8e2824eb
diff --git a/src/config.h.in b/src/config.h.in
new file mode 100644
index 0000000..518e520
--- /dev/null
+++ b/src/config.h.in
@@ -0,0 +1,6 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define PROJECT_VERSION "@PROJECT_VERSION@"
+
+#endif // CONFIG_H