[PATCH] Fix for issue #4234, svndumpfilter exclude --targets wants pathname to start with '/'

 From the issue[1] description,

<snip>

When svndumpfilter exclude command accepts path prefixes starting with either /<pathname>
or just <pathname>, I expect it to work the same way when we use with --targets option.

For Eg :

Both of the following command works fine when we directly provide the
path prefix

$ cat sample.dump | svndumpfilter exclude /tags > filtered4.dump

$ cat sample.dump | svndumpfilter exclude tags > filtered4.dump

However, when we use targets, it seems to be a must to prefix all the path prefixed with
a / which is not mentioned anywhere in the documentation as well.

</snip>

Attaching the patch and log message to fix this issue.

Thanks & Regards,
Vijayaguru

[1] http://subversion.tigris.org/issues/show_bug.cgi?id=4234