archrelease: call 'svn copy' once for all files

We don't need to invoke svn copy on each file; it accepts multiple
arguments. This cut Allan's time releasing one patch-friendly package
from 5 minutes to 2 minutes.

Signed-off-by: Dan McGee <dan@archlinux.org>
Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>