libbtrfsutil: comment out fd_converter()

Recent changes to the python code reworked path_converter() so that it
does not use fd_converter() anymore. Assuming it may be used in the
future again comment it out.

Signed-off-by: David Sterba <dsterba@suse.com>

libbtrfsutil/python/module.c

@@ -19,6 +19,7 @@
 
 #include "btrfsutilpy.h"
 
+#if 0
 static int fd_converter(PyObject *o, void *p)
 {
 	int *fd = p;
@@ -40,6 +41,7 @@ static int fd_converter(PyObject *o, void *p)
 	*fd = tmp;
 	return 1;
 }
+#endif
 
 int path_converter(PyObject *o, void *p)
 {