Remove unnecessary POINTER attribute.

src/libmtime.f90

@@ -1968,7 +1968,7 @@ contains
   !!
   !! @param[out]       errno       optional, error message     
   subroutine timedeltaToString(my_timedelta, string, errno) !OK-TESTED.
-    type(timedelta), pointer :: my_timedelta
+    type(timedelta), target :: my_timedelta
     character(len=max_timedelta_str_len) :: string
     type(c_ptr) :: dummy_ptr
     integer :: i