Remove the confusing crap that allowed a filter using the libavfilter
bridge to be compiled without libavfilter. Instead, compile the wrappers
only if libavfilter is enabled at compile time.
The only filter which still requires it is vf_stereo3d (unfortunately).
Special-case this one. (The whole filter and how it interacts with lavfi
is pure braindeath anyway.)
Some filters exists only to create a specific lavfi graph. Allow these
filters to reset the graph exactly on reconfig, and allow them to modify
some image parameters too. Also make vf_lw_update_graph() behave like
vf_lw_set_graph() - they had a subtitle difference with filter==NULL.
Useful for the following commit.
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.
This will allow old filter to run libavfilter instead by calling
vf_lw_set_graph(), which turns the filter into a wrapper, using a given
libavfilter graph.
Later commits use that to automatically "reroute" a bunch of filters to
libavfilter. We want to get rid of the old MPlayer filter code, because
it's bad an unmaintained, but we still don't want to force everyone to
use vf_lavfi, so this solution will do for a while.
wm4