Add FILE_STORAGE_DIR to be in lib/_autoconf.py

Author: manuel.franceschini
Reviewed-by: iustinp

lib/Makefile.am

@@ -19,6 +19,7 @@ _autoconf.py: Makefile
 	  echo "OS_SEARCH_PATH = [$(OS_SEARCH_PATH)]"; \
 	  echo "XEN_KERNEL = '$(XEN_KERNEL)'"; \
 	  echo "XEN_INITRD = '$(XEN_INITRD)'"; \
+	  echo "FILE_STORAGE_DIR = '$(FILE_STORAGE_DIR)'"; \
 	} > $@
 
 pre-check: all