debugger: deadlock in the java EDT due to the debug mode fixed

debugger: deadlock in the java EDT due to the debug mode fixed

  f=figure("closerequestfcn","disp(""closing""); close(gcf()); disp(""close done !"")");
  debug

  click on the close button of the figure

  the EDT is waiting for the execution of the closerequestfcn
  because storing a command in debug mode pause the thread.
  When the main thread of Scilab execute close, the close function
  wants to add something in the EDT which is paused.

Change-Id: I0996465dd9f9965e3ef05c845260c533aded6348