bug#11703: 23.4; `grep-compute-defaults' passes useless, incompatible "-e" flag to "xargs -0"

[Chong Yidong]

Samuel Bronson <naesten@gmail.com> writes:

> Unfortunately, BSD xargs does not accept `-e', so with it Emacs falls
> back to using `find -exec', which gives less-convenient-to-edit command
> lines (since this puts the grep pattern somehere way in the middle of
> the `find' command, rather than at the end).
>
> Furthermore, this use of `-e' seems to be rather pointless, since GNU
> xargs does not appear to have actually done this logical EOF processing
> when `-0' was active within recorded history.

I've committed your patch to trunk.  Thanks.