Add missing lib dependency on X11.

Bug: b/36882554
Change-Id: I723d8c2876b963b43429d4fa322d6e09380d8f32
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/267001
Reviewed-by: Oleh Prypin <oprypin@google.com>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37339}

modules/desktop_capture/BUILD.gn

@@ -179,6 +179,7 @@ if (rtc_include_tests) {
 
     if (is_linux || is_chromeos) {
       sources += [ "screen_drawer_linux.cc" ]
+      libs = [ "X11" ]
     }
 
     if (is_mac) {