the mp_log is freed when the corresponding mpv_handle (ta_parent) is
freed in the EventHelper, though it could still be used from different
threads. instead don't use a ta_parent and manually free on manual
dereferencing. on app shutdown (memory cleanup) this is not called but
instead is freed by the usual cleanup and freeing.
the LogHelper is only able to be manually dereferenced in the AppHub,
so no race conditions are possible in all other cases (vo).in the AppHub
it's impossible to hit a race condition atm, because of how the init
process works and how/where the log is used. only manually forcing
logging in the exit process itself could theoretically trigger a use
after free.
Fixes#13823
since cocoa is initialising mpv and does several things before the mpv
core does anything and the mpv_handle was passed to the App, this can be
used to log such things before the mpv logging is available. helpful for
debugging especially bundle related things.
the logger mapping looks a bit unintuitive but error is basically yellow
what our warning is and fatal is red what our error is.
