Auto merge of #47431 - ehuss:beta, r=alexcrichton

bors · bors · commit 8035321e1b7f · 2018-01-18T01:56:09.000Z
Update cargo on beta. This brings in rust-lang/cargo#4940 which adds `"workspace_root"` to `cargo metadata` so that tools can resolve the new relative paths in symbols and compiler messages.
diff --git a/src/tools/cargo b/src/tools/cargo
@@ -1 +1 @@
-Subproject commit a88fbace48ac42ab21e1d8609012480d0aeab982
+Subproject commit 64326d735a0c883ad6aa0a2c49fe12b5b61307e1
