pull-user-20211220

Richard Henderson

@rth7680

3363615a · meson: Move bsd_user_ss to bsd-user/ · Dec 20, 2021

Move errno processing from safe_syscall() to safe_syscall_base().
Move safe_syscall() from linux-user to common-user.
Add FreeBSD support to safe_syscall_base().
Tidy top-level meson.build wrt {bsd,linux}-user.