Auto merge of #95678 - pietroalbini:pa-1.62.0-bootstrap, r=Mark-Simulacrum

Bump bootstrap compiler to 1.61.0 beta

This PR bumps the bootstrap compiler to the 1.61.0 beta. The first commit changes the stage0 compiler, the second commit applies the "mechanical" changes and the third and fourth commits apply changes explained in the relevant comments.

r? `@Mark-Simulacrum`

diff --cc library/core/src/char/methods.rs
Simple merge

diff --cc library/core/src/intrinsics.rs
Simple merge

diff --cc library/core/src/slice/mod.rs
Simple merge

diff --cc library/core/src/str/mod.rs
Simple merge