0340d3ad2d
Some packages like libpfring assume the presense of lex, which on some
other systems is a symlink to flex but not all. Symlink flex to fix
compilation.
Arch Linux and Fedora do this as far as I know.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
(backported from 7ef38e42c8)