Adds default (mock) Context Hub HAL 1.2 impl

Also refactors common code.

Bug: 166845383
Test: Compile only (VTS test coming up in future CL)
Change-Id: Iae6cf09e2fffb854af61c29e6004ceb062a892b3
diff --git a/contexthub/common/default/1.X/Android.bp b/contexthub/common/default/1.X/Android.bp
new file mode 100644
index 0000000..691a1b7
--- /dev/null
+++ b/contexthub/common/default/1.X/Android.bp
@@ -0,0 +1,28 @@
+//
+// Copyright (C) 2020 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_headers {
+    name: "android.hardware.contexthub@1.X-common-impl",
+    vendor_available: true,
+    defaults: ["hidl_defaults"],
+    export_include_dirs: ["."],
+    shared_libs: [
+        "android.hardware.contexthub@1.0",
+        "libbinder",
+        "libcutils",
+        "libhidlbase",
+        "libutils",
+    ],
+}