[linux-x86] Refresh prebuilts for aarch64

Change-Id: I6307b98e0d3666f0df8f64d09886f5e112000828
GCC: 4.9 (pre-release)
Binutils: 2.24
GDB: 7.7

(cherry picked from commit 7823f2a1a406d5e73462b9161db0f9f43131cfef)
diff --git a/toolchain.mk b/toolchain.mk
new file mode 100644
index 0000000..2ecc24c
--- /dev/null
+++ b/toolchain.mk
@@ -0,0 +1,17 @@
+# Copyright (C) 2014 The Android Open Source Project
+#
+# 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.
+
+LOCAL_PATH := $(call my-dir)
+
+include $(call all-makefiles-under, $(LOCAL_PATH))