cmake-gui: Wait for configure/generate thread to complete before exiting.

A prevous fix to interrupt granularity makes it so we don't have to wait very long.

Source/QtDialog/CMakeSetupDialog.cxx

@@ -288,7 +288,7 @@ CMakeSetupDialog::~CMakeSetupDialog()
 
   // wait for thread to stop
   this->CMakeThread->quit();
-  this->CMakeThread->wait(2000);
+  this->CMakeThread->wait();
 }
 
 bool CMakeSetupDialog::prepareConfigure()