Use match expression directly in guide.md

Use a match expression directly in the println statement, instead of creating a second variable.
Update LLVM to get slightly better memcpy elision
Check for borrow of local variable introduced within static block.

(Rather than ICE on it.)

Fix #18118.
Fix misaligned carot in guide
Fix warning in Struct sync::Mutex example

let mut value = mutex.lock();
warning: variable does not need to be mutable
Mark lt as inline in PartialOrd
Fix fold explanation in the guide

The explanation of fold talks about three elements that should be summed, but it uses different values in the provided code.
auto merge of #18120 : jrincayc/rust/match_exp, r=thestinger

Use a match expression directly in the println statement, instead of creating a second variable.  It seems weird that the current guide.md complains about creating an extra variable, when the same feature could be demonstrated without creating the extra variable.
auto merge of #18123 : dotdash/rust/llvm_memcpy, r=alexcrichton
auto merge of #18124 : pnkfelix/rust/fsk-add-check-of-borrow-local-static, r=thestinger

Check for borrow of local variable introduced within static block.

(Rather than ICE on it.)

Fix #18118.
auto merge of #18135 : EduardoBautista/rust/fix-misaligned-carot, r=steveklabnik
auto merge of #18136 : mprobinson/rust/example-warning, r=alexcrichton

let mut value = mutex.lock();
warning: variable does not need to be mutable
auto merge of #18138 : rclanan/rust/mark-lt-partialord-inline, r=sfackler

Fixes issue #18090
auto merge of #18139 : JelteF/rust-1/patch-1, r=steveklabnik

The explanation of fold talks about three elements that should be summed, but it uses different values in the provided code.
Remove a number of deprecated crates

All of these crates have been deprecated for some time and properly live in the
rust-lang organization as cargo-based crates.

To update your code, depend on the rust-lang/foo repository via cargo.

[breaking-change]
Remove a large amount of deprecated functionality

Spring cleaning is here! In the Fall! This commit removes quite a large amount
of deprecated functionality from the standard libraries. I tried to ensure that
only old deprecated functionality was removed.

This is removing lots and lots of deprecated features, so this is a breaking
change. Please consult the deprecation messages of the deleted code to see how
to migrate code forward if it still needs migration.

[breaking-change]
Test fixes and rebase conflicts