Clean up USE_NEON to make it easier to disable NEON for benchmarking

Bug: 27242871
Change-Id: I30ba8bfe55885cde531706c760ec27e593d7f8b3
diff --git a/services/audioflinger/Android.mk b/services/audioflinger/Android.mk
index 6e3eb83..302e4dc 100644
--- a/services/audioflinger/Android.mk
+++ b/services/audioflinger/Android.mk
@@ -127,6 +127,9 @@
 
 LOCAL_MODULE := libaudioresampler
 
+# uncomment to disable NEON on architectures that actually do support NEON, for benchmarking
+#LOCAL_CFLAGS += -DUSE_NEON=false
+
 include $(BUILD_SHARED_LIBRARY)
 
 include $(call all-makefiles-under,$(LOCAL_PATH))
diff --git a/services/audioflinger/AudioResamplerFirOps.h b/services/audioflinger/AudioResamplerFirOps.h
index 658285d..2a26496 100644
--- a/services/audioflinger/AudioResamplerFirOps.h
+++ b/services/audioflinger/AudioResamplerFirOps.h
@@ -26,11 +26,15 @@
 #endif
 
 #if defined(__aarch64__) || defined(__ARM_NEON__)
+#ifndef USE_NEON
 #define USE_NEON (true)
-#include <arm_neon.h>
+#endif
 #else
 #define USE_NEON (false)
 #endif
+#if USE_NEON
+#include <arm_neon.h>
+#endif
 
 template<typename T, typename U>
 struct is_same
diff --git a/services/audioflinger/AudioResamplerSinc.cpp b/services/audioflinger/AudioResamplerSinc.cpp
index e93c064..f600d6c 100644
--- a/services/audioflinger/AudioResamplerSinc.cpp
+++ b/services/audioflinger/AudioResamplerSinc.cpp
@@ -43,10 +43,14 @@
 #endif
 
 #if defined(__aarch64__) || defined(__ARM_NEON__)
-#include <arm_neon.h>
-#define USE_NEON
+#ifndef USE_NEON
+#define USE_NEON (true)
+#endif
 #else
-#undef USE_NEON
+#define USE_NEON (false)
+#endif
+#if USE_NEON
+#include <arm_neon.h>
 #endif
 
 #define UNUSED(x) ((void)(x))
@@ -417,7 +421,7 @@
 
     size_t count = offset;
 
-#ifndef USE_NEON
+#if !USE_NEON
     int32_t l = 0;
     int32_t r = 0;
     for (size_t i=0 ; i<count ; i++) {