Use cpu_relax() implementation for aarch64 (#11677)

Motivation:

We only implement cpu_relax() for x86_64 atm, we should also do for aarch64

Modifications:

Add implementation

Result:

Possible better performance on aarch64 when busy spinning with epoll is used

transport-native-epoll/src/main/c/netty_epoll_native.c

@@ -287,6 +287,8 @@ static jint netty_epoll_native_epollWait0(JNIEnv* env, jclass clazz, jint efd, j
 static inline void cpu_relax() {
 #if defined(__x86_64__)
     asm volatile("pause\n": : :"memory");
+#elif defined(__aarch64__)
+    asm volatile("isb\n": : :"memory");
 #endif
 }