Add generic Android target to test Android boot flow

Android boot flow is currently not being built in the reference project.
This means it does not get built in presubmit/continuous builds either.
Add a dummy Android target to remedy that.

Change-Id: Iba6cc9d877249ac0b149cf12bbc3fbc4d11494da
diff --git a/BUILD.gn b/BUILD.gn
index f4c684a..4a5acf0 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -18,6 +18,7 @@
 group("root") {
   deps = [
     "//src:hafnium(:aem_v8a_fvp_clang)",
+    "//src:hafnium(:android_aarch64_clang)",
     "//src:hafnium(:qemu_aarch64_clang)",
     "//src:hafnium(:rpi4_clang)",
   ]
@@ -101,3 +102,20 @@
     core_freq_mhz = 500
   }
 }
+
+# Generic target which uses the Android boot flow. It is not intended to run on
+# any Android platform. It exists only to test building Android-specific code.
+aarch64_toolchains("android_aarch64") {
+  cpu = "cortex-a57"
+  origin_address = "0x0"
+  boot_flow = "//src/boot_flow:android"
+  console = "//src/arch/aarch64/pl011"
+  iommu = "//src/iommu:absent"
+  gic_version = 2
+  heap_pages = 60
+  max_cpus = 8
+  max_vms = 16
+  toolchain_args = {
+    pl011_base_address = "0x09000000"
+  }
+}
diff --git a/android_aarch64/BUILD.gn b/android_aarch64/BUILD.gn
new file mode 100644
index 0000000..b8bff16
--- /dev/null
+++ b/android_aarch64/BUILD.gn
@@ -0,0 +1,16 @@
+# Copyright 2020 The Hafnium Authors.
+#
+# 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
+#
+#     https://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.
+
+source_set("android_aarch64") {
+}