restore non-freebsd-unix fix for profiling (#57249)
Restores #57035, undo #57089 for non-FreeBSD. While I suggested doing
this change for all platforms, I forgot that means non-FreeBSD platforms
become vulnerable again to the very deadlock problems that #57035 was
required to prevent. That fix seems to not be viable on FreeBSD due to
known libc implementation problems on that platform. However, upon
closer inspection of the questionable design implementation decisions
they seem to have made here, the platform is likely not currently
vulnerable to this libunwind bug in the first place:
https://github.com/lattera/freebsd/blob/master/libexec/rtld-elf/rtld_lock.c#L120
