Use #[prelude_import] in libcore and libstd

[jseyfried]

r? @eddyb

[jseyfried]

c.f. #34108
cc @petrochenkov

[eddyb]

@bors r+

[bors]

📌 Commit 2b0ea00 has been approved by eddyb

[petrochenkov]

Nice!

[bors]

☔ The latest upstream changes (presumably #35766) made this pull request unmergeable. Please resolve the merge conflicts.

[jseyfried]

@bors r=eddyb

[bors]

📌 Commit a9a2979 has been approved by eddyb

[bors]

⌛ Testing commit a9a2979 with merge eaf71f8...

[bors]

💔 Test failed - auto-win-gnu-32-opt-rustbuild

[jseyfried]

@bors retry

[bors]

⚡ Previous build results for auto-linux-cross-opt, auto-win-msvc-64-cargotest are reusable. Rebuilding only auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-cargotest, auto-linux-64-cross-freebsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-no-mir, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt, auto-win-msvc-64-opt-no-mir, auto-win-msvc-64-opt-rustbuild...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-cargotest, auto-linux-64-cross-freebsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-no-mir, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-no-mir, auto-win-msvc-64-opt-rustbuild
Approved by: eddyb
Pushing eaf71f8 to master...