Bugfix/file object file size type (#116)

* Fix file object example file size type

* Add include for definition of BACnet unsigned.

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

src/bacnet/basic/object/bacfile.h

@@ -39,6 +39,7 @@
 #include "bacnet/bacnet_stack_exports.h"
 #include "bacnet/bacdef.h"
 #include "bacnet/bacenum.h"
+#include "bacnet/bacint.h"
 #include "bacnet/apdu.h"
 #include "bacnet/arf.h"
 #include "bacnet/awf.h"
@@ -108,7 +109,7 @@ extern "C" {
     void bacfile_init(
         void);
     BACNET_STACK_EXPORT
-    uint32_t bacfile_file_size(
+    BACNET_UNSIGNED_INTEGER bacfile_file_size(
         uint32_t instance);
 
     /* handling for read property service */