mwan3: update to version 1.5-9

Fix issue where config file would be overwritten in some cases
Fix issue where local address of wan point-to-point links were unreachable from lan

Signed-off-by: Jeroen Louwes <jeroen.louwes@gmail.com>
Merge pull request #685 from Adze1502/master

mwan3: update to version 1.5-9
btrfs-progs: improve init script

check for btrfs in /proc/filesystems instead of /proc/modules

Signed-off-by: Daniel Golle <daniel@makrotopia.org>