[time.syn] Move treat_as_floating_point_v next to treat_as_floating_point. (#3533)

Author: brycelelbach

source/time.tex

@@ -84,10 +84,11 @@
   namespace chrono {
     // \ref{time.traits}, customization traits
     template<class Rep> struct treat_as_floating_point;
-    template<class Rep> struct duration_values;
     template<class Rep>
       inline constexpr bool treat_as_floating_point_v = treat_as_floating_point<Rep>::value;
 
+    template<class Rep> struct duration_values;
+
     template<class T> struct is_clock;
     template<class T> inline constexpr bool is_clock_v = is_clock<T>::value;