Update Cargo.lock with new comment; suppress 29244.

changes/bug29244

@@ -0,0 +1,4 @@
+  o Minor bugfixes (build, compatibility):
+    - Update Cargo.lock file to match the version made by the latest
+      version of Rust, so that "make distcheck" will pass again.
+      Fixes bug 29244; bugfix on 0.3.3.4-alpha.

src/rust/Cargo.lock

@@ -1,3 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
 [[package]]
 name = "external"
 version = "0.0.1"