cpp: added univalue.h to include because it was causing compiler crash

Author: D33r-Gee

src/common/settings.h

@@ -10,6 +10,7 @@
 #include <cstddef>
 #include <map>
 #include <string>
+#include <univalue.h>
 #include <vector>
 
 class UniValue;