Moved CPU architecture check from Tor plugin to plugin factory.

This allows us to avoid instantiating the plugin on unsupported
architectures.

briar-android/src/net/sf/briar/plugins/tor/TorPlugin.java

@@ -113,12 +113,6 @@ class TorPlugin implements DuplexPlugin, EventHandler {
 	}
 
 	public boolean start() throws IOException {
-		// Check that we have a Tor binary for this architecture
-		if(!Build.CPU_ABI.startsWith("armeabi")) {
-			if(LOG.isLoggable(INFO))
-				LOG.info("No Tor binary for this architecture");
-			return false;
-		}
 		// Try to connect to an existing Tor process if there is one
 		try {
 			controlSocket = new Socket("127.0.0.1", CONTROL_PORT);

briar-android/src/net/sf/briar/plugins/tor/TorPluginFactory.java

@@ -8,6 +8,7 @@ import net.sf.briar.api.plugins.duplex.DuplexPlugin;
 import net.sf.briar.api.plugins.duplex.DuplexPluginCallback;
 import net.sf.briar.api.plugins.duplex.DuplexPluginFactory;
 import android.content.Context;
+import android.os.Build;
 
 public class TorPluginFactory implements DuplexPluginFactory {
 
@@ -31,6 +32,8 @@ public class TorPluginFactory implements DuplexPluginFactory {
 	}
 
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		// Check that we have a Tor binary for this architecture
+		if(!Build.CPU_ABI.startsWith("armeabi")) return null;
 		return new TorPlugin(pluginExecutor,appContext, shutdownManager,
 				callback, MAX_FRAME_LENGTH, MAX_LATENCY, POLLING_INTERVAL);
 	}