Remove now invalid note in 1992/brnstnd/Makefile

As yesterday I fixed the entry to compile with modern systems the
Makefile does not need a note that it might not compile with modern
systems.

1991/brnstnd/Makefile

@@ -185,7 +185,6 @@ all: data ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
-	@echo "NOTE: This entry might not compile when using modern compilers."
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
 
 # alternative executable