include <algorithm> for std::fill_n

Index: rts/System/SpringHashSet.hpp
--- rts/System/SpringHashSet.hpp.orig
+++ rts/System/SpringHashSet.hpp
@@ -10,6 +10,7 @@
 #include <cstdlib> // malloc
 #include <iterator>
 #include <utility>
+#include <algorithm>
 
 #define DCHECK_EQ_F(a, b)
 #define DCHECK_LT_F(a, b)
