stats: move the limits stuff into the types.hh file

src/base/stats/types.hh

@@ -31,6 +31,7 @@
 #ifndef __BASE_STATS_TYPES_HH__
 #define __BASE_STATS_TYPES_HH__
 
+#include <limits>
 #include <vector>
 
 #include "sim/host.hh"
@@ -42,6 +43,8 @@ typedef double Counter;
 /** vector of counters. */
 typedef std::vector<Counter> VCounter;
 
+typedef std::numeric_limits<Counter> CounterLimits;
+
 /** All results are doubles. */
 typedef double Result;
 /** vector of results. */