BUILD: atomic: add string.h for memcpy() on ARM64
As reported in issue #686, ARM64 build fails since the include files
reorganization. This is caused by the lack of string.h while a memcpy()
is present in __ha_cas_dw().
diff --git a/include/haproxy/atomic.h b/include/haproxy/atomic.h
index ca3f24f..3f26b6a 100644
--- a/include/haproxy/atomic.h
+++ b/include/haproxy/atomic.h
@@ -23,6 +23,8 @@
#ifndef _HAPROXY_ATOMIC_H
#define _HAPROXY_ATOMIC_H
+#include <string.h>
+
/* A few notes for the macros and functions here:
* - this file is painful to edit, most operations exist in 3 variants,
* no-thread, threads with gcc<4.7, threads with gcc>=4.7. Be careful when