fix gcc-6 build on os x (pytorch#297)

szagoruyko · apaszke · commit 04393cd47da5 · 2016-12-12T00:01:15.000+01:00
diff --git a/torch/lib/libshm/socket.h b/torch/lib/libshm/socket.h
@@ -7,6 +7,7 @@
 #include <string>
 #include <sstream>
 #include <iostream>
+#include <cstring>
 
 #include "err.h"
 #include "alloc_info.h"
