Add macro UNUSED() to bt_utils.h

Also include bt_utils.h in some other header files commonly
included by some subsystems.

Change-Id: I1e6be2abae503c4303c92d97eeeb29981beacd10
Signed-off-by: Mike J. Chen <mjchen@google.com>
diff --git a/audio_a2dp_hw/Android.mk b/audio_a2dp_hw/Android.mk
index ee113b1..f9fd0a1 100644
--- a/audio_a2dp_hw/Android.mk
+++ b/audio_a2dp_hw/Android.mk
@@ -5,7 +5,7 @@
 LOCAL_SRC_FILES:= \
 	audio_a2dp_hw.c
 
-LOCAL_C_INCLUDES+= .
+LOCAL_C_INCLUDES+= . $(LOCAL_PATH)/../utils/include
 
 LOCAL_SHARED_LIBRARIES := \
 	libcutils liblog
diff --git a/bta/Android.mk b/bta/Android.mk
index f4b8a7e..bca6c08 100644
--- a/bta/Android.mk
+++ b/bta/Android.mk
@@ -98,6 +98,7 @@
                    $(LOCAL_PATH)/../hcis/patchram \
                    $(LOCAL_PATH)/../udrv/include \
                    $(LOCAL_PATH)/../brcm/include \
+                   $(LOCAL_PATH)/../utils/include \
                    $(bdroid_C_INCLUDES) \
 
 
diff --git a/bta/include/utl.h b/bta/include/utl.h
index df08b5a..e26cded 100644
--- a/bta/include/utl.h
+++ b/bta/include/utl.h
@@ -25,6 +25,7 @@
 #define UTL_H
 
 #include "data_types.h"
+#include "bt_utils.h"
 
 /*****************************************************************************
 **  Constants
diff --git a/btif/include/btif_util.h b/btif/include/btif_util.h
index 30bff69..95969dd 100755
--- a/btif/include/btif_util.h
+++ b/btif/include/btif_util.h
@@ -26,6 +26,7 @@
 
 #include "data_types.h"
 #include "bt_types.h"
+#include "bt_utils.h"
 
 /*******************************************************************************
 **  Constants & Macros
diff --git a/utils/include/bt_utils.h b/utils/include/bt_utils.h
index ac18f07..d601f2e 100644
--- a/utils/include/bt_utils.h
+++ b/utils/include/bt_utils.h
@@ -40,4 +40,6 @@
 void bt_utils_cleanup();
 void raise_priority_a2dp(tHIGH_PRIORITY_TASK high_task);
 
+#define UNUSED(x) (void)(x)
+
 #endif /* BT_UTILS_H */