Fixed memory barrier macro check so it isn't quite so fragile
diff --git a/include/SDL_atomic.h b/include/SDL_atomic.h
index bea071c..deee35f 100644
--- a/include/SDL_atomic.h
+++ b/include/SDL_atomic.h
@@ -184,6 +184,7 @@
#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_5TE__)
#ifdef __thumb__
/* The mcr instruction isn't available in thumb mode, use real functions */
+#define SDL_MEMORY_BARRIER_USES_FUNCTION
#define SDL_MemoryBarrierRelease() SDL_MemoryBarrierReleaseFunction()
#define SDL_MemoryBarrierAcquire() SDL_MemoryBarrierAcquireFunction()
#else
diff --git a/src/atomic/SDL_atomic.c b/src/atomic/SDL_atomic.c
index d3327d4..8483bdf 100644
--- a/src/atomic/SDL_atomic.c
+++ b/src/atomic/SDL_atomic.c
@@ -289,7 +289,7 @@
#endif
}
-#if defined(__thumb__) && (defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6T2__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_5TE__))
+#ifdef SDL_MEMORY_BARRIER_USES_FUNCTION
#error This file should be built in arm mode so the mcr instruction is available for memory barriers
#endif
