Add support for atomic operations TAS/S_UNLOCK in aarch64

This was already added to upstream 9.3.0+ version but we need to add this into
pre-upgrade postgresql version (until we are not upgrading also from 9.3.0+).

~> upstream (612ecf311b)
~> #970661

diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index d4a783f..29124b1 100644
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -335,6 +335,29 @@ tas(volatile slock_t *lock)
 #endif	 /* __arm__ */
 
 
+/*
+ * On ARM64, we use __sync_lock_test_and_set(int *, int) if available.
+ */
+#if defined(__aarch64__) || defined(__aarch64)
+#ifdef HAVE_GCC_INT_ATOMICS
+#define HAS_TEST_AND_SET
+
+#define TAS(lock) tas(lock)
+
+typedef int slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+	return __sync_lock_test_and_set(lock, 1);
+}
+
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+#endif	 /* HAVE_GCC_INT_ATOMICS */
+#endif	 /* __aarch64__ */
+
+
 /* S/390 and S/390x Linux (32- and 64-bit zSeries) */
 #if defined(__s390__) || defined(__s390x__)
 #define HAS_TEST_AND_SET