printpath: do not fetch more than PATH_MAX bytes from tracee's memory

printpath: do not fetch more than PATH_MAX bytes from tracee's memory

The kernel does not copy more than PATH_MAX bytes from userspace
pathnames, treating non-NUL-terminated pathnames as ENAMETOOLONG.

* util.c (printpathn): Decrease buffer size to PATH_MAX.
(printpath): Specify PATH_MAX - 1 as the maximum pathname length
to match the kernel behaviour.  The underlying umovestr call will fetch
up to PATH_MAX bytes from tracee's memory, but no more than first
PATH_MAX - 1 bytes will be printed.