Add a glClear() in GHOST/X11 between creating the GLX context and

displaying the window.

This fixes a brief flash of random data on Blender startup on my
system (Ubuntu 11.10, ATI Mobility Radeon HD 5650, Gallium drivers.)

Code review link:
http://codereview.appspot.com/5505071/

intern/ghost/intern/GHOST_WindowX11.cpp

@@ -1345,6 +1345,8 @@ installDrawingContext(
 				s_firstContext = m_context;
 			}
 			glXMakeCurrent(m_display, m_window,m_context);
+			glClearColor(0.447, 0.447, 0.447, 0);
+			glClear(GL_COLOR_BUFFER_BIT);
 			success = GHOST_kSuccess;
 		} else {
 			success = GHOST_kFailure;