Move the C bindings tests to the new location.

mojo/public/c/bindings/tests/BUILD.gn

-# Copyright 2016 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-import("../../../mojo_sdk.gni")
-
-mojo_sdk_source_set("tests") {
-  testonly = true
-
-  sources = [
-    "array_unittest.cc",
-    "buffer_unittest.cc",
-    "message_unittest.cc",
-    "struct_unittest.cc",
-    "testing_util.h",
-    "union_unittest.cc",
-    "validation_unittest.cc",
-  ]
-
-  deps = [
-    "//testing/gtest",
-  ]
-
-  mojo_sdk_deps = [
-    "mojo/public/c:bindings",
-    "mojo/public/cpp/bindings/tests:mojo_public_bindings_test_utils",
-    "mojo/public/cpp/bindings/tests:validation_util",
-    "mojo/public/cpp/test_support",
-    "mojo/public/cpp/system",
-
-    # The "_c" suffix'd target compiles the generated C bindings to this mojom
-    # target.
-    "mojo/public/interfaces/bindings/tests:test_interfaces_c",
-  ]
-}