hal: Increase ffv process thread priority

Set ffv process thread priority to ANDROID_PRIORITY_AUDIO
and set affinity for ffv reader thread to achieve better performance.

CRs-Fixed: 2405913
Change-Id: I04743f705cc78ed5f9378a6a566ec4c485f5dcb0
diff --git a/hal/Android.mk b/hal/Android.mk
index 89efe54..cfec83b 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -494,6 +494,7 @@
     LOCAL_SHARED_LIBRARIES += vendor.qti.hardware.audiohalext@1.0
 endif
 
+LOCAL_CFLAGS += -D_GNU_SOURCE
 LOCAL_CFLAGS += -Wall -Werror
 
 LOCAL_COPY_HEADERS_TO   := mm-audio