about EncodeDateTime() arguments

We currently have

void EncodeDateTime(struct pg_tm * tm, fsec_t fsec, int *tzp, char **tzn, int style, char *str)

but tzn isn't used anywhere, only *tzn is used everywhere.  Wouldn't it
be clearer to remove that one level of indirection and instead have the
signature be

void EncodeDateTime(struct pg_tm * tm, fsec_t fsec, int *tzp, char *tzn, int style, char *str)

or better yet

void EncodeDateTime(struct pg_tm * tm, fsec_t fsec, const int *tzp, const char *tzn, int style, char *str)