Log Message:
Update libmatroska to 1.4.3:

2015-10-17  Moritz Bunkus  <moritz@bunkus.org>

        * Released v1.4.3.

2015-05-02  Daniel Winzen  <d@winzen4.de>

        * all: a couple of optimizations in the main library and a memory
        leak fix in the tests

2015-02-01  Jan Engelhardt  <jengelh@inai.de>

        * build system: fix linking against libEBML