Update to bindfs-1.15.1 from 1.8.4

ChangeLog is too long to paste here:
https://bindfs.org/docs/ChangeLog.utf8.txt

Note: On NetBSD, bindfs always maps the root directory "/" regardless
of what source directory specified, unless the -f (foreground) option
is given. The issue existed in 1.8.4 and I thought updating the
package could fix it, but it didn't. The problem was actually in
librefuse, which is now fixed in HEAD:
http://mail-index.netbsd.org/source-changes/2021/11/30/msg134159.html

(pho)