Writing to readonly page can cause trap 0xc on FreeBSD too.

Submitted-by: Juergen Lock <nox@jelal.kn-bremen.de>
sparc64-bsd-user: sync ccr before changing carry flag

Sync ccr so that changing carry flag manually after syscall works
properly.

Signed-off-by: Juergen Lock <nox@jelal.kn-bremen.de>