Initialise bArbMultisampleSupported as false

Otherwise the code doesn't make sense; InitMultisample() would return
true even if no pixel format was chosen. Found by code reading by me
and Emmanuel, not actually verified on non-multi-sample-capable
hardware.

Change-Id: I7197a1c72768bbf2c928193582104a82808ea53c

vcl/source/opengl/OpenGLContext.cxx

@@ -310,7 +310,7 @@ bool InitMultisample(const PIXELFORMATDESCRIPTOR& pfd, int& rPixelFormat,
         iAttributes[2] = WGL_DRAW_TO_BITMAP_ARB;
     }
 
-    bool bArbMultisampleSupported = true;
+    bool bArbMultisampleSupported = false;
 
     // First we check to see if we can get a pixel format for 8 samples
     valid = wglChoosePixelFormatARB(hDC, iAttributes, fAttributes, 1, &pixelFormat, &numFormats);