The internal libEBML was updated to v1.3.9. That version contains
changes to cmake to build an additional header file, ebml_export.h. In
MKVToolNix, which isn't cmake-based, that file has to be created
manually, and the Rakefile does so.
However, when configure runs the file doesn't exist yet. This means
that any attempt to compile a test program with the internal libebml
will fail due to the header not being found. configure's compilation
checks will therefore fail.
For the detection of libebml::FindNextChild doing a compilation check
against the internal libebml isn't really needed as we know that the
version does include it. So just hardcode that knowledge and avoid the
compilation check.
libEBML v1.3.5 contains the following change:
------------------------------------------------------------
EbmlMaster::CheckMandatory: only fail for default-value-less mandatory elements
The function EbmlMaster::CheckMandatory() will now only return false
if a mandatory element is missing for which there's no default value
in the specifications. This means that callers such as
EbmlMaster::UpdateSize() and by extension EbmlMaster::Render() will
not insist on all mandatory elements being present anymore, but only
those for which there's no default value.
------------------------------------------------------------
This allows mkvmerge, mkvpropedit and the GUI's header editor to only
actually add those elements that have to be added to a master before
writing it to the file. Adding e.g. the TrackLanguage element isn't
necessary anymore if should be set to "eng" anyway as "eng" is its
default value. Before the change libEBML was insisting on it being
present in the "TrackEntry" master, though, no matter what it was set
to.
