nxagent: make nxagentSkipImage a Boolean

nx-X11/programs/Xserver/hw/nxagent/Drawable.c

@@ -123,7 +123,7 @@ unsigned long nxagentGetColor(DrawablePtr pDrawable, int xPixel, int yPixel);
 unsigned long nxagentGetDrawableColor(DrawablePtr pDrawable);
 unsigned long nxagentGetRegionColor(DrawablePtr pDrawable, RegionPtr pRegion);
 
-int nxagentSkipImage = 0;
+Bool nxagentSkipImage = False;
 
 static int nxagentTooManyImageData(void)
 {

nx-X11/programs/Xserver/hw/nxagent/Handlers.c

@@ -153,7 +153,7 @@ struct _DispatchRec nxagentDispatch = { UNDEFINED, 0, 0, 0 };
  * server.
  */
 
-extern int nxagentSkipImage;
+extern Bool nxagentSkipImage;
 
 void nxagentBlockHandler(void * data, struct timeval **timeout, void * mask)
 {
@@ -350,7 +350,7 @@ void nxagentBlockHandler(void * data, struct timeval **timeout, void * mask)
                            nxagentCorruptedBackgrounds > 0 ||
                                nxagentCorruptedPixmaps > 0));
 
-    if (nxagentSkipImage == 0 && synchronize == 1)
+    if (!nxagentSkipImage && synchronize == 1)
     {
       #ifdef TEST
       fprintf(stderr, "nxagentBlockHandler: Setting a zero timeout with [%d][%d][%d] and "