SynEdit: Ifdef Markup: fix missing validate for nodes

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41597 4005530d-fff6-0310-9dd1-cebe43e6787f
SynEdit: Ifdef Markup: set node state, on buffer change

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41598 4005530d-fff6-0310-9dd1-cebe43e6787f