Flac codec link statically against libaudio_utils

Static linking avoids pulling in most of the library, along with the related
downstream dependencies that come with rest of the library.

Bug: 182386024
Test: atest CtsMediaTestCases:android.media.cts.DecoderTest#testFlacIdentity
Test: atest CtsMediaTestCases:android.media.cts.DecoderTest#testDecodeFlac
Change-Id: I0e583100236bf3d68f46dbde275cf57b4d97c31d