Express libmedia dependencies in libmediaplayerservice

libstagefright_nuplayer depends on headers from libmedia although
it is not linked directly against libmedia.

Consumers of libmediaplayerservice must have libmedia's complete
include path as part of their include path in order to consume
libmediaplayerservice.

Bug: 27804373
Change-Id: Ia294129736b3c855191ef255133165b7beaba376
Test: Compiles.