Express libmedia dependencies in stagefright components

libstagefright includes a number of static libraries, each of which
includes eventually includes headers from libmedia.  Express this
dependency explicitly so that the static libraries can pick up
libmedia's header include path.

Bug: 27804373
Test: Compiles.

Change-Id: I0cb17327202f5b8b840eba6fdbd8768e203f16de