Add GN Build Files and Custom Modifications

Issue:https://gitee.com/openharmony/build/issues/I6UFTP
Signed-off-by: lubinglun <lubinglun@huawei.com>

BUILD.gn

@@ -0,0 +1,28 @@
+# Copyright (c) 2023 Huawei Device Co., Ltd.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import("//build/ohos.gni")
+
+ohos_cargo_crate("lib") {
+    crate_name = "rustc_hash"
+    crate_type = "rlib"
+    crate_root = "src/lib.rs"
+
+    sources = ["src/lib.rs"]
+    edition = "2015"
+    cargo_pkg_version = "1.1.0"
+    cargo_pkg_authors = "The Rust Project Developers"
+    cargo_pkg_name = "rustc-hash"
+    cargo_pkg_description = "speed, non-cryptographic hash used in rustc"
+    features = ["std"]
+}