Importing usr.bin/nl

 * Add _SC_LINE_MAX to unistd.h (value of 15 from NetBSD).
 * Add _SC_LINE_MAX case to sysconf(3) in libc.
 * usr.bin/nl itself required no Minix specific changes.

Change-Id: I10f056ccdf4f212beb1272f735f41303e5036c05