util/copy.pl: work around glob quirk in some of earlier 5.1x Perl versions.

In earlier 5.1x Perl versions quoting globs works only if there is
white space. If there is none, it's looking for names starting with ".

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4695)