Use `copy_max_radius` instead of re-computing it

Inst_eddies/set_all_extr.f90

@@ -31,9 +31,9 @@ contains
 
     logical, intent(in):: periodic ! grid is periodic in longitude
 
-    real, intent(in):: ssh(1 - merge(max_radius(1), 0, periodic):, :)
-    ! (1 - max_radius(1):nlon + max_radius(1), nlat) if the grid is periodic
-    ! in longitude, else (nlon, nlat). Sea-surface height, in m.
+    real, intent(in):: ssh(1 - copy_max_radius:, :)
+    ! (1 - copy_max_radius:nlon + copy_max_radius, nlat)
+    ! sea-surface height, in m
 
     ! Local: