tools/flex: disable building shared libfl.so

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42308 3c298f89-4303-0410-b956-a3cf2f4a3e73
tools/bc: add missing dependency on bison

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42309 3c298f89-4303-0410-b956-a3cf2f4a3e73