pax: Terminate loop for empty directory names

Pax can sometimes loop forever. For example:

$ mkdir -p /tmp/src/foo/bar
$ rm -rf /tmp/dst ; mkdir -p /tmp/dst
$ cd /tmp/src
$ echo 'foo/bar/' | /bin/pax -r -w -d -pe "/tmp/dst"
<looping infinitely>

Here, pax(1) infinitely deletes and re-creates /tmp/dst/foo/bar/.

The problem is that chk_path() (bin/pax/file_subs.c), called from
node_creat() also creates the leaf directory when a trailing '/' appears
in the directory name to create. When the execution goes back from
chk_path() to node_creat(), the function still cannot create the leaf
directory (it has been created by chk_path()), so it unlinks it and
calls node_creat() again. The function re-creates it, and so on...

In node_creat() detect trailing slashes and not create a leaf directory,
but only intermediate ones.

PR: 277060
Reviewed by: imp