scripts: eliminate use of find -print0 | xargs -0

scripts: eliminate use of find -print0 | xargs -0

There are a couple of problems with use of something
like "find ... -print0 | xargs -0 ...":

1. Neither the "-print0" find primary nor the "-0"
   xargs option are specified by POSIX.

2. Without use of the "-0" option, handling arbitrary
   input path names with xargs becomes very awkward.

Eliminate this non-POSIX usage by switching to find's
`-exec ... {} +` syntax instead like this:

    find ... -exec ... '{}' +

This IS specified by POSIX, spawns one less process
(the `xargs` utility) and reduces workload on the
shell (no pipeline need be set up).

Although these changes do not eliminate all uses
of xargs, the remaining uses do not employ the "-0"
option and only provide "well-known" pathnames that
do not fall into the awkward xargs escaping category.

These changes are, however, sufficient to remove
the need for the xargs utility to be installed into
the chroot jail (provided, of course, that the hooks
are updated before the jail is).

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>