Add fnl build target

mojo/public/cpp/system/tests/macros_unittest.cc

Index: mojo/public/cpp/system/tests/macros_unittest.cc
diff --git a/mojo/public/cpp/system/tests/macros_unittest.cc b/mojo/public/cpp/system/tests/macros_unittest.cc
index 72a9b242776e52a385c91f04f7be3625ade4d5a4..2508b6f7ce853583abbef80e6679adeb15a1e364 100644
--- a/mojo/public/cpp/system/tests/macros_unittest.cc
+++ b/mojo/public/cpp/system/tests/macros_unittest.cc
@@ -84,6 +84,9 @@ TEST(MacrosCppTest, ArraySize) {
   // the size of the type of the local and not the values itself.
   MOJO_ALLOW_UNUSED_LOCAL(local_array);
   EXPECT_EQ(4u, MOJO_ARRAYSIZE(local_array));
+
+  // Prevent gcc unneeded-internal-declaration warning.
+  MOJO_ALLOW_UNUSED_LOCAL(kGlobalArray);
 }
 
 // Note: MSVS is very strict (and arguably buggy) about warnings for classes