bug#64743: Speed up GNU make's internal processing

[Nick Bowler]

On 20/07/2023, Bruno Haible <bruno@clisp.org> wrote:
> Karl Berry wrote:
>> I just hope those weird-looking %:: rules do not cause trouble with
>> other makes. I guess we'll find out.
>
> I tested the default 'make' of various OSes, before submitting the patch.
> Whether some other, rarely-used 'make' implementation has problems with it,
> we'll find out.

FWIW I tried the makes on FreeBSD 9, HP-UX 11 and ULTRIX 4.5 and there was
no obvious negative effect with the snippet shown in the original post.

I expect all the non-GNU implementations are interpreting these lines
as ordinary target rules for a funnily-named files with funnily-named
prerequisites.  So it's not quite right to say it has "no effect", but
I think it shouldn't cause any particular problem for packages using
portable file names.

Cheers,
  Nick