Enable compilation of angle_end2end_tests on Linux

gpu/gpu.gyp

Index: gpu/gpu.gyp
diff --git a/gpu/gpu.gyp b/gpu/gpu.gyp
index 4e9a76c6d26d507814a55017b9c659e87218d75d..7a4a4c0e2e5694b9552eafc534ed8e3958214010 100644
--- a/gpu/gpu.gyp
+++ b/gpu/gpu.gyp
@@ -706,7 +706,7 @@
         },
       ],
     }],
-    ['OS == "win"', {
+    ['OS == "win" or (OS == "linux" and use_x11)', {
       'targets': [
         {
           # TODO(kbr): port this target to the GN build.
@@ -724,6 +724,10 @@
             'angle_end2end_tests_main.cc',
           ],
         },
+      ],
+    }],
+    ['OS == "win"', {
+      'targets': [
         {
           # TODO(jmadill): port this target to the GN build.
           'target_name': 'angle_perftests',