If a process fails in the background, bash ignores it even when running
with set -e. To address it, we store a token in a file per each rank,
which only gets written when each process finishes properly. Then we
make sure that each rank has completed successfully, otherwise we fail
the test.
Tests can now specify a DRIVER option pointing to a shell script that
will run instead of the default driver. It allows tests to run any
commands and run the emulator several times or with different
environment variables.
The full path of the test program is available in the OVNI_TEST_PATH
environment variable.
