audio: Add flags to makefiles

Enable GCOV if config is set to true. Also
add gcov_flush in source files to get enhanced
code coverage.

Change-Id: I39776cc6d6f16cd23da05b66669eea22fc4cba81
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>
diff --git a/visualizer/offload_visualizer.c b/visualizer/offload_visualizer.c
index a9664b6..9ad8fea 100644
--- a/visualizer/offload_visualizer.c
+++ b/visualizer/offload_visualizer.c
@@ -40,6 +40,18 @@
 
 typedef void (*acdb_send_audio_cal_t)(int, int);
 
+#ifdef AUDIO_FEATURE_ENABLED_GCOV
+extern void  __gcov_flush();
+static void enable_gcov()
+{
+    __gcov_flush();
+}
+#else
+static void enable_gcov()
+{
+}
+#endif
+
 acdb_send_audio_cal_t acdb_send_audio_cal;
 
 enum {
@@ -223,6 +235,7 @@
 
 int lib_init() {
     pthread_once(&once, init_once);
+    enable_gcov();
     return init_status;
 }