use "r" instead of "q"

src/os/unix/ngx_gcc_atomic_amd64.h

diff --git a/src/os/unix/ngx_gcc_atomic_amd64.h b/src/os/unix/ngx_gcc_atomic_amd64.h
index 289cd61..faaf7af 100644
--- a/src/os/unix/ngx_gcc_atomic_amd64.h
+++ b/src/os/unix/ngx_gcc_atomic_amd64.h
@@ -68,7 +68,7 @@
          NGX_SMP_LOCK
     "    xaddq  %0, %1;   "
 
-    : "+q" (add) : "m" (*value) : "cc", "memory");
+    : "+r" (add) : "m" (*value) : "cc", "memory");
 
     return add;
 }