Remove the link to libl which only contains a stub function

on yywrap, if the flex is told yywrap is not in use, then this linkage becomes
unnecessary

sbin/setkey/Makefile

@@ -37,8 +37,6 @@ WARNS?=	1
 CFLAGS+= -I${.CURDIR} -I${SRCTOP}/lib/libipsec
 YFLAGS=	-d
 
-LIBADD=	l
-
 CLEANFILES=	y.tab.c y.tab.h key_test.o keytest
 
 # libpfkey

sbin/setkey/token.l

@@ -67,6 +67,8 @@ int parse(FILE **);
 int yyparse(void);
 %}
 
+%option noyywrap
+
 /* common section */
 nl		\n
 ws		[ \t]+