config: allow chacl to be in any directory in $PATH

config: allow chacl to be in any directory in $PATH

Previously, xfstests checked for chacl in only a few hard-coded
directory: /bin, /sbin, and /usr/bin.  Use set_prog_path to allow
chacl to be in any directory in $PATH, which is how we find the
executable path for most other executables.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>