Revert "Don't test the engine on startup"

This reverts commit ca0dae9.

This is needed because we load the engine to get function pointers for
get_item_info and item_set_cas, then destroy it, which can segfault if
we haven't initialized the engine.

The worst problem is that we create a db in /tmp; we can avoid this by
not loading a database if no dbname is given.

Change-Id: I45deb3dcfa37056e8fd639ef0aaab5b302c91ca0
Reviewed-on: http://review.northscale.com:8080/408
Tested-by: Dustin Sallings <dustin@spy.net>
Reviewed-by: Dustin Sallings <dustin@spy.net>

bucket_engine.c

@@ -341,7 +341,16 @@ static ENGINE_HANDLE *load_engine(const char *soname, const char *config_str,
         return NULL;
     }
 
-    if (engine->interface != 1) {
+    if (engine->interface == 1) {
+        ENGINE_HANDLE_V1 *v1 = (ENGINE_HANDLE_V1*)engine;
+        if (v1->initialize(engine, config_str) != ENGINE_SUCCESS) {
+            v1->destroy(engine);
+            fprintf(stderr, "Failed to initialize instance. Error code: %d\n",
+                    error);
+            dlclose(handle);
+            return NULL;
+        }
+    } else {
         fprintf(stderr, "Unsupported interface level\n");
         dlclose(handle);
         return NULL;