Cygwin: lockf: Fix access violation in lf_clearlock().
The commit
ae181b0ff122 has a bug that the pointer is referred bofore
NULL check in the function lf_clearlock(). This patch fixes that.
Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
Fixes: ae181b0ff122 ("Cygwin: lockf: Make lockf() return ENOLCK when too many locks")
Reported-by: Sebastian Feld <sebastian.n.feld@gmail.com>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>