audio-caf/msm8998: fix missing dependency error

hardware/qcom/audio-caf/msm8998/qahw_api/test/Android.mk: error:
hal_play_test (EXECUTABLES android-arm) missing libpthread
(SHARED_LIBRARIES android-arm)

*) The test code files are thoroughly broken - many compile errors
   owing to things like missing }. Disable compilation of QAHW test apps.

Change-Id: Ib0ccf119d2310681337a802e33dc3bbd652dfefe