The current version of OWnet uses a macro 'OW_CACHE', which hasn't been defined, anywhere. As long as the macro isn't defined, please, consider adapting the code as or similar to the patch given below.
--- owfs-2.9p5/module/ownet/c/src/c/globals.c
+++ owfs-2.9p5/module/ownet/c/src/c/globals.c
@@ -23 +23 @@
-#if OW_CACHE
+#ifdef OW_CACHE
I don't see the OW_CACHE in this file in the current version. OW_CACHE was deprecated as of 2.9p0 or so
OW_CACHE can't be found in the current code, though it still is in the owfs-2.9p5.tar.gz. I suppose it won't be there any longer after packaging the next version.