Apply GitHub PR#73 "Rely on mpv to know where to store application data
& cache" [1] to fix permission errors resulting from write attempts to
/etc.
[1] https://github.com/po5/mpv_sponsorblock/pull/73
Commits:
60f4c8f517445fd2e2ab11677bfad992132686df
cce913bf3887c2b4a1bd862c6204b13640d5df96
Signed-off-by: Florian Albrechtskirchinger <falbrechtskirchinger@gmail.com>