Add xdisplaycheck back until //build dependency is removed

tools/xdisplaycheck/BUILD.gn

Index: tools/xdisplaycheck/BUILD.gn
diff --git a/tools/xdisplaycheck/BUILD.gn b/tools/xdisplaycheck/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..779e16365195d35191a60e2d1abd42812344d1b2
--- /dev/null
+++ b/tools/xdisplaycheck/BUILD.gn
@@ -0,0 +1,15 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+executable("xdisplaycheck") {
+  sources = [
+    "xdisplaycheck.cc",
+  ]
+
+  configs += [ "//build/config/linux:x11" ]
+
+  deps = [
+    "//build/config/sanitizers:deps",
+  ]
+}