afsd: print syscalls on separate lines with afsd -debug

afsd: print syscalls on separate lines with afsd -debug

afsd prints information to standard out for testing and debugging when the
-debug option is given. However, syscall tracing is emitted without trailing
newlines on all platforms except netbsd, creating an unreadable wall of text.

    # afsd -debug
    ...
    afsd: Forking 4 background daemons.
    SScall(183, 28, 0)=0 183, 28, 6583200)=0 SScall(183, 28, 6583
    200)=0 SScall(183, 28, 6583200)=0 SScall(183, 28, 6583200)=0 S
    Scall(183, 28, 6583200)=0 SScall(183, 28, 6583200)=0 SScall(18
    ...

Make the syscall call tracing usable by printing each one on a separate line.

    # afsd -deubg
    ...
    afsd: Forking 4 background daemons.
    SScall(183, 28, 0)=0 183, 28, 6583200)=0
    SScall(183, 28, 6583200)=0
    SScall(183, 28, 6583200)=0
    ...

Change-Id: Ic9208243c1e05352744fb6f575384e00d0e3e59c
Reviewed-on: https://gerrit.openafs.org/12385
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>