Don't desync with the default encoder configuration.

The allow_lowbitdepth shouldn't be exported to the API at all.
This is a temporary hack to allow API users such as the analyzer,
inspector, and simple_decoder.c to function correctly.

Change-Id: Id171cc0c24d78216647e949a1dc30a81f4cc826d
diff --git a/av1/av1_dx_iface.c b/av1/av1_dx_iface.c
index 98923d8..d665a3a 100644
--- a/av1/av1_dx_iface.c
+++ b/av1/av1_dx_iface.c
@@ -106,6 +106,8 @@
          (ctx->init_flags & AOM_CODEC_USE_FRAME_THREADING))
             ? 1
             : 0;
+    // TODO(tdaede): this should not be exposed to the API
+    priv->cfg.allow_lowbitdepth = CONFIG_LOWBITDEPTH;
     if (ctx->config.dec) {
       priv->cfg = *ctx->config.dec;
       ctx->config.dec = &priv->cfg;