TAChart: Restore previous compiler hint status after Unused procedure

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41783 4005530d-fff6-0310-9dd1-cebe43e6787f
TAChart: Avoid 'unused variable' hint on platfrorms other than Win32 and Gtk2

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41784 4005530d-fff6-0310-9dd1-cebe43e6787f