android: use __ARM_NEON instead of __ARM_NEON__ to include <arm_neon.h>

Only __ARM_NEON is defined with Android NDK and arm64-v8a
Tested on ndk-r18, ndk-r13 and also Xcode.
(Visual Studio needs a different fix).

Fixes Bugzilla #4409.

include/SDL_cpuinfo.h

@@ -54,7 +54,7 @@
 #if defined(HAVE_ALTIVEC_H) && defined(__ALTIVEC__) && !defined(__APPLE_ALTIVEC__) && defined(SDL_ENABLE_ALTIVEC_H)
 #include <altivec.h>
 #endif
-#if defined(__ARM_NEON__) && !defined(SDL_DISABLE_ARM_NEON_H)
+#if defined(__ARM_NEON) && !defined(SDL_DISABLE_ARM_NEON_H)
 #include <arm_neon.h>
 #endif
 #if defined(__3dNOW__) && !defined(SDL_DISABLE_MM3DNOW_H)

src/audio/SDL_audiotypecvt.c

@@ -26,7 +26,7 @@
 #include "SDL_assert.h"
 
 /* !!! FIXME: disabled until we fix https://bugzilla.libsdl.org/show_bug.cgi?id=4186 */
-#if 0 /*def __ARM_NEON__*/
+#if 0 /*def __ARM_NEON */
 #define HAVE_NEON_INTRINSICS 1
 #endif