Fix build error on Ubuntu 16.04

diff --git a/src/client/content_mapblock.cpp b/src/client/content_mapblock.cpp
index f7d20001f41d33eb3c494d31c225260efd2a71e4..3d06584c4ec9a5aa2215cc428cc6c91cc97358b3 100644 (file)
--- a/src/client/content_mapblock.cpp
+++ b/src/client/content_mapblock.cpp
@@ -17,6 +17,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
+#include <cmath>
 #include "content_mapblock.h"
 #include "util/numeric.h"
 #include "util/directiontables.h"