Fixed uninitialised variable in x11 null cursor creation

Fully initialised color var.
Clarified intent a little with comments/layout.

platform/x11/os_x11.cpp

@@ -534,22 +534,26 @@ Error OS_X11::initialize(const VideoMode &p_desired, int p_video_driver, int p_a
 	}
 
 	{
-		Pixmap cursormask;
-		XGCValues xgc;
-		GC gc;
-		XColor col;
-		Cursor cursor;
+		// Creating an empty/transparent cursor
+
+		// Create 1x1 bitmap
+		Pixmap cursormask = XCreatePixmap(x11_display,
+				RootWindow(x11_display, DefaultScreen(x11_display)), 1, 1, 1);
 
-		cursormask = XCreatePixmap(x11_display, RootWindow(x11_display, DefaultScreen(x11_display)), 1, 1, 1);
+		// Fill with zero
+		XGCValues xgc;
 		xgc.function = GXclear;
-		gc = XCreateGC(x11_display, cursormask, GCFunction, &xgc);
+		GC gc = XCreateGC(x11_display, cursormask, GCFunction, &xgc);
 		XFillRectangle(x11_display, cursormask, gc, 0, 0, 1, 1);
-		col.pixel = 0;
-		col.red = 0;
-		col.flags = 4;
-		cursor = XCreatePixmapCursor(x11_display,
-				cursormask, cursormask,
+
+		// Color value doesn't matter. Mask zero means no foreground or background will be drawn
+		XColor col = {};
+
+		Cursor cursor = XCreatePixmapCursor(x11_display,
+				cursormask, // source (using cursor mask as placeholder, since it'll all be ignored)
+				cursormask, // mask
 				&col, &col, 0, 0);
+
 		XFreePixmap(x11_display, cursormask);
 		XFreeGC(x11_display, gc);