Move adbd authentication into its own library.

As part of moving adbd into a module, split authentication out into a
library with a stable ABI that lives on the system image.

Bug: http://b/137798163
Test: for i in `seq 1 100000`; do echo $i; adb wait-for-device shell "su 0 stop; su 0 start; sleep 10"; adb disconnect; done
Change-Id: I05e3679598e33c83f8cc4c17208f4f753cbfd5e1
diff --git a/libs/adbd_auth/Android.bp b/libs/adbd_auth/Android.bp
new file mode 100644
index 0000000..f68ab5e
--- /dev/null
+++ b/libs/adbd_auth/Android.bp
@@ -0,0 +1,39 @@
+// Copyright (C) 2019 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.
+
+cc_library {
+    name: "libadbd_auth",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Wthread-safety",
+        "-Werror",
+    ],
+    srcs: ["adbd_auth.cpp"],
+    export_include_dirs: ["include"],
+
+    version_script: "libadbd_auth.map.txt",
+    stubs: {
+        symbol_file: "libadbd_auth.map.txt",
+    },
+
+    host_supported: true,
+    recovery_available: true,
+
+    shared_libs: [
+        "libbase",
+        "libcutils",
+        "liblog",
+    ],
+}