Use Use templetized operations for Score and Value

Note that in value we leave two specialized functions
to allow adding an integer, we don't want to add this
as a template becasue we want to control implicit
conversions to integer of an enum.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/types.h

@@ -137,6 +137,9 @@ inline void operator-- (T& d, int) { d = T(int(d) - 1); }
 template<typename T>
 inline void operator+= (T& d1, const T d2) { d1 = d1 + d2; }
 
+template<typename T>
+inline void operator-= (T& d1, const T d2) { d1 = d1 - d2; }
+
 template<typename T>
 inline void operator*= (T& d, int i) { d = T(int(d) * i); }