uip/scansbr.c: Add PUTC() macro, similar to FPUTS().
uip/scansbr.c: Add PUTC() macro, similar to FPUTS().

FPUTS() exists, but all the putc(3) checks for error were written
alongside in longhand.  May as well have a PUTC() to match, though
perhaps just the existing check of the FILE's sticky error state with
ferror(3) is sufficient and neither macro is required.

mcr/nmh,mcr/nmh