Add a -s flag for the same functionality as strace. Introduce a Name

Add a -s flag for the same functionality as strace.  Introduce a Name
type which is a String type that has no -s limitations applied to it.
Change most Strings in the code to Names and add a few extra syscalls,
namely munmap, read, rename and symlink.  This was enough to facilitate
following file descriptor allocations in the code more easily and
getting a hint at what's being read/written from/to files.  More
syscalls should really be added.

While here, fix an off-by-one bug in the buffer truncation code and
add a fflush so that truss's output reflects the syscall that the
program is stuck in.

Sponsored by:	Sophos/Activestate
MFC after:	2 weeks