gdb: remove trailing empty line in target-delegates.c

gdb: remove trailing empty line in target-delegates.c

In a review [1], I pointed out that applying the patch, git would say:

    .git/rebase-apply/patch:147: new blank line at EOF.

However, since the empty line is in target-delegates.c (a generated
file), there's nothing the author can do about it.  To avoid this
comment coming up again in the future, change make-target-delegates.py
to avoid the trailing empty line.  Do this by making it output empty
lines before each entity, not after.

Since this needs removing a newline output in gdbcopyright, adjust
ada-unicode.py and gdbarch.py to avoid changes in the files they
generate.

[1] https://inbox.sourceware.org/gdb-patches/20230427210113.45380-1-jhb@FreeBSD.org/T/#m083598405bef19157f67c9d97846d3dd90dc7d1c

Change-Id: Ic4c648f06443b432168cb76603402c918aa6e5d2
Approved-By: Tom Tromey <tom@tromey.com>