This update for libebml, libmatroska fixes the following issues:

- Update libeml to version 1.3.9:
* Fixed the handling of Unicode codepoints > U+FFFF
* Some build system related changes
* Fix memory leak (boo#1104354)

- Update libmatroska to version 1.5.2:
* KaxBlock: fixed a potential access to invalid memory due to
invalid lace sizes read from invalid data.
* KaxBlock: fixed a potential null pointer dereference triggerable
by reading invalid data. (boo#1141027)
* Compatibilty with libEBML 1.3.7
* Switched to cmake.
* KaxBlockGroup, KaxSimpleBlock: fixed writing the block header
* Setting the version number in the "KaxCodeVersion" variable
* KaxSemantic: add new elements dealing with 360°/VR content and

This update was imported from the openSUSE:Leap:15.1:Update update project.