QEMU has something that claims to be linux-user support for
the unicore32 guest CPU. However the syscall numbers in
linux-user/unicore32 are nothing like those actually implemented
in the upstream kernel (which uses asm-generic syscall numbers).
We should either fix our unicore32 support to use the real
syscall numbers, or just drop it; since nobody has touched
linux-user/unicore32 since 2012, and there have been no
commits to target-unicore32 that aren't generic "clean up
all targets" type patches since 2012 or 2013, and nobody
has ever complained that the syscall numbers are all broken,
my initial inclination is to say we should just drop this.