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
diff --git a/media/ndk/Android.bp b/media/ndk/Android.bp
index 8267ba5..e355183 100644
--- a/media/ndk/Android.bp
+++ b/media/ndk/Android.bp
@@ -104,6 +104,7 @@
             enabled: false,
         },
     },
+    version_script: "libmediandk.map.txt",
 }
 
 llndk_library {