Fix build on gcc 5.0 (#7586)

src/mapgen/mg_ore.cpp

@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "map.h"
 #include "log.h"
 #include "util/numeric.h"
+#include <cmath>
 #include <algorithm>
 
 

src/network/connection.cpp

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <iomanip>
 #include <cerrno>
 #include <algorithm>
+#include <cmath>
 #include "connection.h"
 #include "serialization.h"
 #include "log.h"

src/util/srp.cpp

@@ -27,6 +27,9 @@
  */
 
 // clang-format off
+
+#include <cstddef>
+
 #ifdef WIN32
 	#include <windows.h>
 	#include <wincrypt.h>