Check if /etc/machinefeatures exists before setting $MACHINEFEATURES

mjf.csh

-setenv MACHINEFEATURES /etc/machinefeatures
+if ( -d /etc/machinefeatures ) then
+  setenv MACHINEFEATURES /etc/machinefeatures
+endif
 if ( "$PBS_JOBID" != "" ) then
   setenv JOBFEATURES $HOME/jobfeatures-$PBS_JOBID
 endif

mjf.sh

-export MACHINEFEATURES=/etc/machinefeatures
+if [ -d /etc/machinefeatures ] ; then
+  export MACHINEFEATURES=/etc/machinefeatures
+fi
 if [ "$PBS_JOBID" != "" ] ; then
   export JOBFEATURES=$HOME/jobfeatures-$PBS_JOBID
 fi