add TorService.torFreeAll() method to clean up between restarts

This is here as an experiment in case it is useful in Java space.  It is
looking like there are better ways to handle the shutdown, so my guess is
that this will not be useful.

* guardianproject/tor-android#59
* guardianproject/tor-android#61 (comment)
* guardianproject/tor-android#57

src/feature/api/org_torproject_jni_TorService.c

@@ -258,6 +258,16 @@ Java_org_torproject_jni_TorService_runMain
 {
   return RunMain(env, thisObj);
 }
+
+JNIEXPORT void JNICALL
+Java_org_torproject_jni_TorService_torFreeAll
+(JNIEnv *env, jobject _ignore)
+{
+  UNUSED(env);
+  UNUSED(_ignore);
+  tor_free_all(0);
+}
+
 /**
  * Android does not support UNIX Domain Sockets, but we can fake it by sending
  * the file descriptor via a java.io.FileDescriptor instance, which can be

src/feature/api/org_torproject_jni_TorService.h

@@ -62,6 +62,15 @@ JNIEXPORT jint JNICALL
 Java_org_torproject_jni_TorService_runMain
 (JNIEnv *, jobject);
 
+/*
+ * Class:     org_torproject_jni_TorService
+ * Method:    torFreeAll
+ * Signature: ()V
+ */
+JNIEXPORT void JNICALL
+Java_org_torproject_jni_TorService_torFreeAll
+(JNIEnv *, jobject);
+
 /*
  * Class:     org_torproject_jni_TorService
  * Method:    prepareFileDescriptor