Convert Android.mk to Android.bp

This commit converts Android.mk to Android.bp.

Besides, during the transition, we found that $(wificond_cpp_flags)
should be $(wifi_system_cflags).

Bug: 37429084
Test: Sailfish builds, boots, and wifi works.
Change-Id: Ida255cd6ac0cd9434bd95f1ae570683dccb0388e
diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..60aff26
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,17 @@
+// Copyright (C) 2017 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.
+
+subdirs = [
+    "libwifi_system",
+]