RE: Add missing copyright for pg_upgrade/t/* files

Dear David,

> It is great to make sure each file has the Copyright and I see this
> patch has already been committed.

Thanks!
While checking more, I was surprised because I found many files which do not
have Copyright via " grep -Lr Copyright --exclude-dir .git ..." command.
I'm not sure whether it is expected, but all sql files in src/test/regress/sql and
many files in contrib do not have. Do you know something about it?

> Just curious, is there a rule to add Copyright to Postgres?

Sorry, I'm not sure about it. Before submitting a patch I have checked the
manual that "PostgreSQL Coding Conventions", but I could not find any.

> For example,
> if I run a command `grep -rn Copyright --include="*.pl" | awk -F ':'
> {'print $2, $1'} | sort -nr` inside postgres/src/bin, It seems most
> Copyright were added to the second line, but these two were added to the
> very beginning (of course, there are three other files following this
> pattern as well).

There seems a tendency that Copyright for recently added files have added it to
the very beginning, but I can suspect from the result that there are no specific
rules about it.

```
$ grep -rn Copyright --include="*.pl" | awk -F ':' {'print $2'} | sort -nr | uniq -c
      1 753
      1 752
      1 717
...
     22 3
    158 2
     24 1
```

Best Regards,
Hayato Kuroda
FUJITSU LIMITED