Re: Detection of hadware feature => please do not use signal

I wrote:
> Early returns are that they're all picking the +simd option, and
> seem to be just as happy with that as they were without it.
> I wonder if we could just drop the "without" probe altogether.
> It'd save some configure cycles for other platforms (since they'll
> fruitlessly run through all of these tests).

Now that we have a nearly-complete census of the buildfarm,
the end result is that they are all happy with the +simd
spelling ... except for one.  "gull" rejects it:
  clang: error: unsupported argument 'armv8-a+crc+simd' to option '-march='
But without +simd it's okay, so removing the other spelling
would cause a performance regression on that machine.

I find this a bit surprising, because gull is using a reasonably
recent compiler (clang version 17.0.4).  We have much older
clang versions that accept +simd --- but they are all aarch64.
gull seems to be our only representative of clang on arm32.
So this seems like a gcc vs clang difference that we'll have
to put up with.

Anyway, I think this thread is now closed: nothing more to do
unless someone thinks of a platform we need more bespoke code
for.

            regards, tom lane