x86_64: Add atomic funtions

This patch adds atomic functions for x86_64.

Change-Id: I298c760a1e6efa2ce2c61a143f833b6785805442
Signed-off-by: Qiming Shi <qiming.shi@intel.com>
diff --git a/include/cutils/atomic-inline.h b/include/cutils/atomic-inline.h
index ae79e00..4f90ef1 100644
--- a/include/cutils/atomic-inline.h
+++ b/include/cutils/atomic-inline.h
@@ -47,8 +47,10 @@
 #include <cutils/atomic-arm64.h>
 #elif defined(__arm__)
 #include <cutils/atomic-arm.h>
-#elif defined(__i386__) || defined(__x86_64__)
+#elif defined(__i386__)
 #include <cutils/atomic-x86.h>
+#elif defined(__x86_64__)
+#include <cutils/atomic-x86_64.h>
 #elif defined(__mips__)
 #include <cutils/atomic-mips.h>
 #else