nethack: use bison + flex instead of yacc + lex during build

packages/nethack/sys-unix-Makefile.utl.patch

@@ -0,0 +1,18 @@
+--- ../Makefile.utl.orig	2020-10-11 10:23:01.057406272 +0200
++++ ./sys/unix/Makefile.utl	2020-10-11 10:25:46.353406154 +0200
+@@ -111,11 +111,11 @@
+ 
+ # yacc/lex programs to use to generate *_comp.h, *_lex.c, and *_yacc.c.
+ # if, instead of yacc/lex you have bison/flex, comment/uncomment the following.
+-YACC     = yacc
+-LEX      = lex
+-# YACC     = bison -y
++# YACC     = yacc
++# LEX      = lex
++YACC     = bison -y
+ # YACC     = byacc
+-# LEX      = flex
++LEX      = flex
+ 
+ # these are the names of the output files from YACC/LEX. Under MS-DOS
+ # and similar systems, they may differ