Fix setup.csh to properly check if LD_LIBRARY_PATH is defined.

setup.csh

@@ -11,7 +11,7 @@ set MYDIR=`cd $MYDIR && pwd`    # ensure absolute path
 setenv ANALYZER $MYDIR/podd
 setenv HCANALYZER $MYDIR
 # Check if LD_LIBRARY_PATH is defined
-if ( $LD_LIBRARY_PATH == "" ) then
+if ( ! ($?LD_LIBRARY_PATH) ) then
    setenv LD_LIBRARY_PATH ""
 endif
 setenv LD_LIBRARY_PATH "${LD_LIBRARY_PATH}:${ANALYZER}:${HCANALYZER}"