Fix a speed issue in CONFIG_TUNE_BUTTERAUGLI

Fix the speed issue that -DCONFIG_TUNE_BUTTERAUGLI is enabled but
--tune=butteraugli is not used.

Change-Id: I536716964735cac64a21bb1bfdac54df531cbdae
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index ed20447..10a281b 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -2670,7 +2670,7 @@
     }
 
 #if CONFIG_TUNE_BUTTERAUGLI
-    if (loop_count == 0) {
+    if (loop_count == 0 && oxcf->tune_cfg.tuning == AOM_TUNE_BUTTERAUGLI) {
       loop = 1;
       av1_setup_butteraugli_recon(cpi, &cm->cur_frame->buf);
     }