auto merge of #5180 : catamorphism/rust/post-snapshot, r=catamorphism

* Disallow structural records everywhere
* Remove all #[cfg(stage0)] stuff
* Remove the last deprecated modes in libcore
* Un-xfail a test

src/test/pretty/record-trailing-comma.rs

@@ -8,9 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// NOTE this is a pretty-printer bug that I fixed, but it's
-// not in the snapshot yet. After a new snapshot, can un-xfail
-// xfail-pretty
+// xfail-test
 // pp-exact
 struct Thing {
     x: int,

src/test/run-pass/pipe-select-macro.rs

@@ -8,9 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// tjc: un-xfail after snapshot
 // xfail-test
-// xfail-pretty
 
 // Protocols
 proto! foo (