Compile apmanager on Android

Noticeable changes to get apmanager to compile on Android:
- Conditional include headers for D-Bus service constants
  based on the target platform.
- Use firewalld proxy instead of permission_broker proxy on
  Android.
- Use stub shill proxy instead of the real one until libshill-client
  is ready.

Bug: 24164800
TEST=Compile apmanager on both Android and Chrome OS
TEST=Run apmanager on Chrome OS device

Change-Id: I7885323796e0043a1e3cc46c129e2736faf4fced
diff --git a/config.cc b/config.cc
index 7a58698..f3e2027 100644
--- a/config.cc
+++ b/config.cc
@@ -17,7 +17,12 @@
 #include "apmanager/config.h"
 
 #include <base/strings/stringprintf.h>
+
+#if !defined(__ANDROID__)
 #include <chromeos/dbus/service_constants.h>
+#else
+#include "dbus/apmanager/dbus-constants.h"
+#endif  // __ANDROID__
 
 #include "apmanager/daemon.h"
 #include "apmanager/device.h"