This is probably useful.
Note that this includes a small, stupid hack to prevent loading of the
config file if vf_lavfi is not available. The profile by default uses
vf_lavfi, and the config parser will output errors if vf_lavfi is not
available.
As another caveat, we install the example profile even if encoding is
disabled (though we don't load it, since this would print errors).
The only thing that used mp_load_per_file_config() was inside
configfiles.c too, so remove the declaration from core.h and move the
function before its use.
Code for loading "[vo.vdpau]" profiles and similar. The messages printed
on loading change, but other than that, everything should behave about
the same.
There's a single mp_msg() in path.c, but all path lookup functions seem
to depend on it, so we get a rat-tail of stuff we have to change. This
is probably a good thing though, because we can have the path lookup
functions also access options, so we could allow overriding the default
config path, or ignore the MPV_HOME environment variable, and such
things.
Also take the chance to consistently add talloc_ctx parameters to the
path lookup functions.
Also, this change causes a big mess on configfiles.c. It's the same
issue: everything suddenly needs a (different) context argument. Make it
less wild by providing a mp_load_auto_profiles() function, which
isolates most of it to configfiles.c.
Since m_option.h and options.h are extremely often included, a lot of
files have to be changed.
Moving path.c/h to options/ is a bit questionable, but since this is
mainly about access to config files (which are also handled in
options/), it's probably ok.
