Apply version-script to libmediandk library

This change also remove some redundancies in include file
and actualizes list of exported AMEDIAFORMAT_ variables for 29 sdk
version. Also adds AMediaCodec_getBufferFormat to the list.

Bug: http://b/69603741
Test: make
Change-Id: I1fd7d1d3dfdd567aa7398c48117c60344bd5e109