Removing mdctx from the credentials.
diff --git a/BUILD b/BUILD
index bcee870..9c2a24b 100644
--- a/BUILD
+++ b/BUILD
@@ -237,6 +237,7 @@
     "src/core/security/auth.c",
     "src/core/security/base64.c",
     "src/core/security/credentials.c",
+    "src/core/security/credentials_metadata.c",
     "src/core/security/credentials_posix.c",
     "src/core/security/credentials_win32.c",
     "src/core/security/google_default_credentials.c",