pipeline: Don't use yield ASM intruction on ARM < 7

panda/src/pipeline/thread.I

@@ -232,7 +232,7 @@ relax() {
   YieldProcessor();
 #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64))
   __asm__ __volatile__("pause");
-#elif defined(__arm__) || defined(__aarch64__)
+#elif __ARM_ARCH >= 7
   __asm__ __volatile__ ("yield" ::: "memory");
 #endif
 }