Make just a single reallocation per call instead of one reallocation
per copied chapters. This fixes possible memory leaks on realloc
failures. Also correct the allocation since it needs multiples of
sizeof(AVChapter*) and not sizeof(AVChapter).

Fixes CID700633 and CID700719.

func2_arg is the same as func_arg, except it has one additional
parameter. Change all func_arg callbacks to take that parameter (and
ignore it).

This was replaced with a per-file value in 3c0df905.

Signed-off-by: Mans Rullgard <mans@mansr.com>

By default don't dump every single option on the user, but print only
the basic options.

Add -h long/full to print more options.

Currently it takes a mask and value, such that options for which
(flags & mask) == value.

Change it to take required flags and forbidden flags instead. This is
shorter and simpler to understand.

Don't require every caller to supply them.

This option does not do anything.

Also remove OPT_GRAB, since -isync is the last option using it.

This allows e.g. -c:v h264 to select the libx264 encoder.

show_foo() functions are declared as void show_foo(void), but called as
int show_foo(const char*, const char*).