Auto merge of #35906 - jseyfried:local_prelude, r=eddyb

Use `#[prelude_import]` in `libcore` and `libstd`

r? @eddyb

diff --cc src/libcore/char.rs
Simple merge

diff --cc src/libcore/intrinsics.rs
Simple merge

diff --cc src/libcore/mem.rs
Simple merge

diff --cc src/libcore/ops.rs
Simple merge

diff --cc src/libcore/ptr.rs
Simple merge

diff --cc src/libstd/lib.rs
Simple merge