bug#64735: 29.0.92; find invocations are ~15x slower because of ignores

[sbaugh]

Dmitry Gutov <dmitry@gutov.dev> writes:
>> (my-bench 1 default-directory "")
>
> (("built-in" . "Elapsed time: 1.601649s (0.709108s in 22 GCs)")
>  ("with-find" . "Elapsed time: 1.792383s (1.135869s in 38 GCs)")
>  ("with-find-p" . "Elapsed time: 1.248543s (0.682827s in 20 GCs)")
>  ("with-find-sync" . "Elapsed time: 0.922291s (0.343497s in 10 GCs)"))

Tangent, but:

Ugh, wow, call-process really is a lot faster than make-process.  I see
now why people disliked my idea of replacing call-process with something
based on make-process, this is a big difference...

There's zero reason it has to be so slow... maybe I should try to make a
better make-process API and implementation which is actually fast.
(without worrying about being constrained by compatibility with
something that's already dog-slow)