Make gn check //mojo/public/* pass

mojo/public/c/environment/BUILD.gn

Index: mojo/public/c/environment/BUILD.gn
diff --git a/build/secondary/testing/BUILD.gn b/mojo/public/c/environment/BUILD.gn
similarity index 63%
copy from build/secondary/testing/BUILD.gn
copy to mojo/public/c/environment/BUILD.gn
index 2cafa68a281302c4e07352ce8fd1d63e4ee341dc..669da7d12df297dad9aea346acfdf38082c73877 100644
--- a/build/secondary/testing/BUILD.gn
+++ b/mojo/public/c/environment/BUILD.gn
@@ -2,10 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("gmock_mutant") {
+source_set("environment") {
   sources = [
-    "gmock_mutant.h",  # gMock helpers
+    "async_waiter.h",
+    "logger.h",
   ]
 
-  deps = [ "//base" ]
+  deps = [ "//mojo/public/c/system" ]
 }