Dejagnu override of local_exec may not be necessary any more

The override of local_exec in dejagnu/boards/arm-dejagnu-overrides.exp may not be necessary any more.

It is there to remove the limit of 512000 bytes that was in an older version of DejaGNU.

That limit has been removed since 2016 (https://gcc.gnu.org/legacy-ml/gcc/2019-05/msg00070.html).

More modern versions of Linux ship with a DejaGNU past that date.

Depending on the infrastructure that you care about you may want to remove the override (and benefit from the other changes that have been made in this procedure since then).

Just figured it would be worth checking whether this is still necessary -- I know it was "on the verge of being unnecessary" a few years ago when I last had contact with this bit of code.