std::function needs <functional>. Fixes Android build

diff --git a/source/validate_cfg.cpp b/source/validate_cfg.cpp
index 136cbdc..a1e86bb 100644 (file)
--- a/source/validate_cfg.cpp
+++ b/source/validate_cfg.cpp
@@ -29,6 +29,7 @@
 #include <cassert>
 
 #include <algorithm>
+#include <functional>
 #include <unordered_map>
 #include <unordered_set>
 #include <utility>