Apply version-script to libaaudio library.

In previous attempt it was mistakenly applied to cc_library_header
instead of the actual library. Do it correctly this time.
The intention of this change is to hide unintentionally
exported symbols from the library.

Bug: http://b/69603741
Test: make
Change-Id: I47967abea0b39aec05e80823c9eb3fe53f9fa591