stubby: appdata_dir not created by init script

[totkeks]

Maintainer: unknown

Environment: aarch64_cortex-a53, SNAPSHOT r28091-77cfe8fd15, BananaPi R4

Description:
Stubby uses /var/lib/stubby as it's default appdata_dir in the configuration to store the trust anchors or keys or something.

Unfortunately, on my device and probably many others /var/ is located in memory and will be gone after a reboot.

I don't know if there is a common way in OpenWrt to handle this use case, so I just came up with this workaround in /etc/init.d/stubby in start_service():

local appdata_dir
config_get appdata_dir "global" appdata_dir ""

mkdir -p "$appdata_dir"
chown stubby:stubby "$appdata_dir"
chmod 0700 "$appdata_dir"

If there are no other ideas, I would create a pull request for this.