Fix typo in csh version

data/etc/cern_profile.d/cern_env.csh

@@ -15,7 +15,7 @@ setenv LHCBDOC /eos/project/l/lhcbwebsites/www/projects
 setenv LHCBNIGHTLIES /cvmfs/lhcbdev.cern.ch/nightlies
 
 # For grid usage
-if ( ! -n ?$X509_CERT_DIR ) then
+if ( ! -n $?X509_CERT_DIR ) then
   if ( -d /etc/grid-security/certificates ) then
     setenv X509_CERT_DIR /etc/grid-security/certificates
   elif ( -d /cvmfs/lhcb.cern.ch/etc/grid-security/certificates ) then