LCL: fixed TScrollingWinControl.AutoScroll endless loop when one scrollbars needs to be shown because of the other

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45082 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL: TControlScrollBar.ClientSizeWithoutBar: removed workaround for gtk2

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45083 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: removed gtk2 workaround

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45084 4005530d-fff6-0310-9dd1-cebe43e6787f