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