jni: fix typo (and crash) from recent factorize

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

vlc-android/jni/libvlcjni.c

@@ -244,7 +244,7 @@ void jni_detach_thread()
 
 int jni_get_env(JNIEnv **env)
 {
-    return (*myVm)->GetEnv(myVm, (void **)&env, VLC_JNI_VERSION) == JNI_OK ? 0 : -1;
+    return (*myVm)->GetEnv(myVm, (void **)env, VLC_JNI_VERSION) == JNI_OK ? 0 : -1;
 }
 
 // FIXME: use atomics