some header files (e.g., <err.h>) include <machine/something.h>, and this
will not pick up the right header files, so it may be removed eventually
anyway. But some people who are not willing to build the right way
apparantly want this, so this is for them.
Correct usage: one of {-p pid, command} is required.
Open output file when command line is fully analyzed: incorrect `truss -o f'
command does not create an empty file anymore.
