Fix plugin loading

Change-Id: I3572f8bc1c90c5f0697054497bde52e4cbc4e71e
related-to-bug:32815560
diff --git a/include/media/PluginLoader.h b/include/media/PluginLoader.h
index 7d54ce4..360af2d 100644
--- a/include/media/PluginLoader.h
+++ b/include/media/PluginLoader.h
@@ -43,7 +43,7 @@
             while ((pEntry = readdir(pDir))) {
                 String8 file(pEntry->d_name);
                 if (file.getPathExtension() == ".so") {
-                    String8 path = pluginDir + pEntry->d_name;
+                    String8 path = pluginDir + "/" + pEntry->d_name;
                     T *plugin = loadOne(path, entry);
                     if (plugin) {
                         factories.push(plugin);
@@ -77,7 +77,8 @@
                 libraries.push(library);
                 return createFactoryFunc();
             } else {
-                ALOGE("Failed to create plugin factory from %s", path);
+                ALOGE("Failed to create plugin factory from %s at entry %s: %s",
+                        path, entry, library->lastError());
             }
         }
         return NULL;