When I build vlc 3.0 with clang 5, I get "mkv error: cannot find KaxSegment or missing mandatory KaxInfo."

[Oleg Lelchuk]

Of course, vlc 3.0 is not available in the ports tree yet, but I am just
curious what I should do in order to get rid of the "mkv error: cannot find
KaxSegment or missing mandatory KaxInfo" issue if I build vlc 3.0 with
clang 5. This patch "#define MKV_IS_ID( el, C ) ( EbmlId( (*el) ) ==
C::ClassInfos.GlobalId )" only works for vlc 2.x, but not for vlc 3.x. I
get compiler errors if I apply this patch. Of course, I have no issues if I
simply build vlc 3.0 with gcc7 instead of clang, but I am just curious how
to get rid of this mkv demuxer issue when I build vlc with clang. Thank you
in advance for answering my question.