Emit uprintf() output for initproc if there is no controlling terminal

[arichardson]

Summary

This patch helped me debug why /sbin/init was not being recognized by the
image activator in CheriBSD.

[jhb]

Adding @kib in case he has any thoughts, but this looks ok to me. A larger change would perhaps be to set a tty for initproc earlier, but I'm not sure what that would break.

[kib]

I do not think that real init ever opens ctty (but something like /bin/sh specified as init can). You can move the check and printf() block before proctree lock, and return right after printf is done.

BTW why don't you return vprintf() value?

[arichardson]

• Apply review suggestions