Fixes <https://issues.guix.gnu.org/55806>.
* gnu/system/install.scm (%installation-services): Refactor into a
procedure, so that it can capture the system it's installing for.
Conditionally add uvesafb-service-type based on whether v86d is
supported by the target architecture.
(installation-os)[services]: Use the %installation-service procedure.
(uvesafb-shepherd-service): Remove %host-type checks.
Signed-off-by: Florian Pelz <pelzflorian@pelzflorian.de>
0aa4311790