When dgn_comp.l and lev_comp.l are processed by older versions of
flex, 'gcc -Wunused' complains when compiling dgn_lex.c and lev_lex.c
because flex creates 'static void yyunput()' and nethack doesn't use
it. Newer versions honor macro YY_NO_UNPUT to hide the offending
code, but that doesn't help with older versions (like the one
masquerading as 'lex' on OSX). Adding a dummy usage would probably
cause problems with other lexers, so change it from static to
'void yyunput()' as a 'sed' fixup in util/Makefile after flex has
finished. That will be a no-op when yyunput doesn't exist or isn't
static.
In addition to the sys/unix/Makefile.utl change, this checks in new
sys/share/{dgn,lev}_lex.c with the fixup in place.