Avoid reallocating name when checking for trailing slash in ZipFile.getEntryPos

getEntryPos does this:

                /* Add slash and try once more */
                name = Arrays.copyOf(name, name.length + 1);
                name[name.length - 1] = '/';
                hsh = hash_append(hsh, (byte)'/');

A trivial optimization to ZipFile.getEntryPos would be to only copy the name array after finding a match for the re-calculated hash value. This removes an allocation and array copy on every miss.