Allow using on XWayland. (jordansissel#355)

This removes behavior introduced by jordansissel#341.

After jordansissel#341 was released, several folks reported that xdotool has indeed
worked correctly on XWayland in the past.

I've left the "is on wayland?" detection code that is otherwise now
unused, in case we want it later.

Fixes jordansissel#346.

xdo.c

@@ -119,10 +119,12 @@ xdo_t* xdo_new_with_opened_display(Display *xdpy, const char *display,
 
   // This library and xdotool do not work correctly on Wayland/XWayland.
   // Try to detect XWayland and warn the user about problems.
-  if (appears_to_be_wayland(xdpy)) {
-    fprintf(stderr, "The X server at %s appears to be XWayland. Unfortunately, XWayland does not correctly support the features used by libxdo and xdotool.\n", display);
-    return NULL;
-  }
+  // TODO(sissel): This was disabled due to issue #346
+  //  -- xdotool works on XWayland for some operations, so it isn't helpful to refuse all usage on XWayland.
+  //if (appears_to_be_wayland(xdpy)) {
+    //fprintf(stderr, "The X server at %s appears to be XWayland. Unfortunately, XWayland does not correctly support the features used by libxdo and xdotool.\n", display);
+    //return NULL;
+  //}
 
 
   /* XXX: Check for NULL here */