LinuxServer Changes:
Rebase to Alpine 3.9, fix init logic to only chown once.
tvheadend Changes:
en50221: fix menu text decoding
getmenutext() checks that dvb_get_string() returns greater than 0, but
that function returns 0 on success.
This causes menu text decoding to always fail, resulting in no menu
texts.
Fix the check to match dvb_get_string() behavior.