Merge pull request #1598 from gmile/alpine-build

Explicitly include sys/types.h
diff --git a/src/cc/ns_guard.h b/src/cc/ns_guard.h
index 65acd65..ce4b61b 100644
--- a/src/cc/ns_guard.h
+++ b/src/cc/ns_guard.h
@@ -18,6 +18,7 @@
 #pragma once
 
 #include <memory>
+#include <sys/types.h>
 
 #include "file_desc.h"