Fix checkwrite for csh.

This is for issue #4139.
I tested the lcg-cp (and lcg-del) command used in checkwrite on tcsh by hand before this fix and it fails with error:
lcg-cp: No match.
After the fix (escaping the "?" in the PFN) it doesn't fail anymore. So I guess that's all we needed. And Daniele also said that the problem is the "?" sign (https://hypernews.cern.ch/HyperNews/CMS/get/computing-tools/26.html)