b=22360 Check for file_operations .flush fl_owner_t id parameter

b=22360  Check for file_operations .flush fl_owner_t id parameter

i=johann

Since 2.6.18 (commit 75e1fcc0b18df0a65ab113198e9dc0e98999a08c) the
file_operations .flush() method has taken an fl_owner_t id parameter.
This is backported to some older vendor kernels, so a simple kernel
version check, as usual, is not sufficient to determine whether this
parameter is present or not.