🌱 GN: Look at all target outputs when detecting duplicates

tools/gn/BUILD.gn

Index: tools/gn/BUILD.gn
diff --git a/tools/gn/BUILD.gn b/tools/gn/BUILD.gn
index 37bce8d89035705820edc6e528ee26cc723b256b..cbc16afef2b483e4ab9342cf066883518e0ff2eb 100644
--- a/tools/gn/BUILD.gn
+++ b/tools/gn/BUILD.gn
@@ -285,6 +285,7 @@ test("gn_unittests") {
     "loader_unittest.cc",
     "ninja_action_target_writer_unittest.cc",
     "ninja_binary_target_writer_unittest.cc",
+    "ninja_build_writer_unittest.cc",
     "ninja_copy_target_writer_unittest.cc",
     "ninja_create_bundle_target_writer_unittest.cc",
     "ninja_group_target_writer_unittest.cc",
@@ -324,6 +325,7 @@ test("gn_unittests") {
     ":gn_lib",
     "//base/test:run_all_unittests",
     "//base/test:test_support",
+    "//testing/gmock",
     "//testing/gtest",
   ]
 }