Generate the java-21-openjdk portable from the c10s sources into the
a10s-portable branch: RHEL has not shipped the 21.0.12.1.1-2 update to
UBI 8 yet, so the portable at portablerelease 2 cannot be built from c8.
The portable specfile is identical in c8s, c9s and c10s.
Only %undefine pkgos is needed now; the riscv64 bits the old
config-portable-riscv64.yaml carried (debug_package, ARCH_DATA_MODEL,
ExclusiveArch, the RPM 4.19 %files fix) are all upstream.
