build-gnu.sh: `/usr/bin/timeout` should not be hardcoded to /usr/bin location

[zhitkoff]

coreutils/util/build-gnu.sh

Line 85 in f1ec8e6

sed -i 's|^"\$@|/usr/bin/timeout 600 "\$@|' build-aux/test-driver

On MacOS Ventura (Version 13.5 (22G74), Apple Silicon) the timeout utility does not exist in /usr/bin and it is not possible to add it there (either by symlink or copy binary) without disabling system protection. This would probably be the case for most MacOS variants.
It is possible to add it to /usr/local/bin, but since build-gnu.sh hardcodes it to /usr/bin/timeout - that would not help.
Would it be better to either let shell to find timeout via PATH or check a couple system locations first and pick one that exists (i.e. check /usr/bin , /usr/local/bin ) ?
Workaround for now is to just edit build-aux/test-driver after it was generated or modify build-gnu.sh in local before running

[tertsdiepraam]

That might indeed be better. We just need to make sure that we're using the system timeout not the uutils one. I suspect that's why it's written this way.

For context the absolute path was introduced here: #1766