ARM gnu toolchain for bare metal arm32 target is only available for x86_64 and aarch64 hosts. Introduce a new option to disable packages using this toolchain on unsupported hosts. [Romain: improve commit log] Signed-off-by: Bryce Johnson <bryce@redpinelabs.com> Signed-off-by: Romain Naour <romain.naour@smile.fr>