added cmath for GCC 5.4

3rdParty/rocksdb/rocksdb/util/options_builder.cc

@@ -4,6 +4,7 @@
 //  of patent rights can be found in the PATENTS file in the same directory.
 
 #include <math.h>
+#include <cmath>
 #include <algorithm>
 #include "rocksdb/options.h"
 

arangod/Aql/TraversalNode.cpp

@@ -30,8 +30,6 @@
 #include "Aql/TraversalOptions.h"
 #include "Indexes/Index.h"
 
-#include <cmath>
-
 using namespace arangodb::basics;
 using namespace arangodb::aql;
 

lib/Basics/Common.h

@@ -147,6 +147,7 @@ typedef long suseconds_t;
 #endif
 
 #include <algorithm>
+#include <cmath>
 #include <functional>
 #include <map>
 #include <set>