For now, return 1 for container-based compilers.  This will change as
soon as ROMs will be buildable with them.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220929114231.583801-18-alex.bennee@linaro.org>