sparc: fix interrupt enable/disable code

The manually written code was all wrong (missing branch delay slots,
wrong type of return instruction used, probably more bugs). Use the same
approach as x86 to have inline functions instead, which is much better
for performance and simpler to write.

Change-Id: Iac0fc814c15311658f983da58ac7f9d3edd75b81
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3595
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

sparc: add defines and minimum set of required files

Gets the stage0 bootstrap to run.
Imlementation is probably nonsense at this point.

Change-Id: I10876efbb54314b864c0ad951152757cdb2fd366
Reviewed-on: https://review.haiku-os.org/c/1061
Reviewed-by: waddlesplash <waddlesplash@gmail.com>