We should not rely on host installed bison/flex for target code. This
ensures better reproducibility of generated code.
http://lists.busybox.net/pipermail/buildroot/2020-November/296786.html
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>