externhelp: replaced DoDirSeparators with DoPathDelims

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42683 4005530d-fff6-0310-9dd1-cebe43e6787f
tests: replaced DoDirSeparators with DoPathDelims

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42684 4005530d-fff6-0310-9dd1-cebe43e6787f