Fixed warning AC_PROG_LEX without either yywrap or noyywrap is obsolete

Ticket: CFE-2780
Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>

Author: larsewi

configure.ac

@@ -143,7 +143,7 @@ m4_ifdef([LT_INIT],
   [AC_DISABLE_STATIC
    AC_PROG_LIBTOOL])
 
-AM_PROG_LEX
+AC_PROG_LEX(noyywrap)
 AC_PROG_YACC
 AC_PROG_INSTALL
 AC_PATH_PROG([PERL], [perl])