flex is build as a tool inside the build system, so use it.
[florian: bump package revision]
Signed-off-by: Waldemar Brodkorb <mail@waldemar-brodkorb.de>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/packages@36105 3c298f89-4303-0410-b956-a3cf2f4a3e73
