Update submodules to point to rust-lang repos
Add eof to MemReader and BufReader

It's easy to figure out and useful as a sanity check sometimes.
Fix ICE on const of nullable enum with fields in null case.

That is, if you have an enum type that is subject to the nullable
pointer optimization, but the null variant has a nonzero number of
fields, and you declare a static whose value is of that variant, then
that used to be an ICE but this change fixes it.
auto merge of #11436 : alexcrichton/rust/update-forks, r=huonw

We're not moving everything just yet, but it's good to start somewhere!
auto merge of #11437 : sfackler/rust/mem-eof, r=alexcrichton

It's easy to figure out and useful as a sanity check sometimes.
auto merge of #11441 : jld/rust/enum-nullable-const-null-with-fields, r=alexcrichton

That is, if you have an enum type that is subject to the nullable
pointer optimization, but the null variant has a nonzero number of
fields, and you declare a static whose value is of that variant, then
that used to be an ICE but this change fixes it.
"As long an iterator" => "As long as an iterator"
Fix #11421
auto merge of #11451 : kud1ing/rust/patch-1, r=cmr
auto merge of #11452 : derekchiang/rust/fix-11421, r=cmr

Closes #11421.  A pretty trivial fix.
fix uninstall target with configurable rustlib directory