uip/scansbr.c: Replace uses of SBUFSIZ with NMH_BUFSIZ.
uip/scansbr.c: Replace uses of SBUFSIZ with NMH_BUFSIZ.

Now that the former is defined as the latter, the uses of SBUFSIZ were
all in the same expression and it simplifies from a ternary expression
to NMH_BUFSIZ.

mcr/nmh,mcr/nmh