Add pointer to extended-help entry for `-C help` codegen options.
Remove binary field
Move replace and swap to std::mem. Get rid of std::util

Also move Void to std::any, move drop to std::mem and reexport in
prelude.
auto merge of #11956 : edwardw/rust/issue-7556, r=cmr

Closes #7556.

Also move ``std::util::Void`` to ``std::any::Void``. It makes more sense to me.
auto merge of #12153 : pnkfelix/rust/fsk-add-dash-C-help-pointer, r=sanxiyn

(The fact that this flag has a large collection of suboptions qualifies it for an entry in the "Additional help" section.)
Revert non-license changes as part of 0ebe112b

The commit accidentally modified the snapshot script which changed its behavior
and is currently blocking a snapshot.
auto merge of #12173 : alexcrichton/rust/fix-snap, r=brson

The commit accidentally modified the snapshot script which changed its behavior
and is currently blocking a snapshot.
auto merge of #12155 : sanxiyn/rust/binary, r=pnkfelix

The field is unused.