DivxDrmDecrypt: Export the header\include file

- Export DivXDrmDecrypt.h which is needed by mm-parser
  for generating libDivxDrm
- libDixDrm is needed to play encrypted divx DRM
  content

Change-Id: Ia9859e2dcc49ce7895ebe5ebf1b28a36e612d00d
(cherry picked from commit 0c7cee4259b58ea43cb38b3e1d11fb8279b46c36)