util,tests: Added exit code to the compiler tests

util,tests: Added exit code to the compiler tests

This testing script should return a non-exit code when one of the
compilations fail.

Change-Id: Ie15bc5779372dd31d784eaffdee4b04abb9a1b11
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32097
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>