Revert "Rewrite atomic.h to use stdatomic.h."

This reverts commit cb344d464009337c283431dec4441b70481d1a49.

Change-Id: Ib17cd8d00695062177ce863cedc4ec7148012317
diff --git a/libcutils/atomic.c b/libcutils/atomic.c
index d34aa00..1484ef8 100644
--- a/libcutils/atomic.c
+++ b/libcutils/atomic.c
@@ -14,13 +14,6 @@
  * limitations under the License.
  */
 
-/*
- * Generate non-inlined versions of android_atomic functions.
- * Nobody should be using these, but some binary blobs currently (late 2014)
- * are.
- * If you read this in 2015 or later, please try to delete this file.
- */
-
 #define ANDROID_ATOMIC_INLINE
 
-#include <cutils/atomic.h>
+#include <cutils/atomic-inline.h>