ramfs@.service required randd as requires_weak, which doesn't enforce
readiness ordering. When ramfs called std::random before randd registered
/scheme/rand, it panicked with 'failed to generate random data'.
Changed requires_weak to requires so init waits for randd to register
its scheme before starting ramfs.
Also patched Rust stdlib sys/random/redox.rs to fall back to xorshift64
seeded from ASLR rather than panicking when /scheme/rand is unavailable.
This is a belt-and-suspenders fix: even with proper ordering, the stdlib
should not panic on missing entropy during early boot.
vasilito
b1022dfa39