aaudio examples: make tests portable to O

Workaround for a recent change in the build that made command line apps
incompatible with O.

Test:  adb shell aaudio_loopback -?
Test:  should print help and not crash
Change-Id: If2a2288249a33c16fa5004b6b7db1a5ff9e22745
Merged-In: If2a2288249a33c16fa5004b6b7db1a5ff9e22745