Auto merge of #109335 - Mark-Simulacrum:stable-next, r=Mark-Simulacrum
[stable] 1.68.1 release
This packages up a set of release notes, version bump, and backports of:
* Don't eagerly convert principal to string #108162
* Revert "enable ThinLTO for rustc on x86_64-pc-windows-msvc dist builds" #109094
* Create dirs for build_triple #109111
* Fix linker detection for clang with prefix #109156
* ci: use apt install --download-only for solaris debs #108951
The last of those is not yet stable-accepted but I expect it to be, we will drop it and rebuild artifacts if we don't actually approve it.
r? `@Mark-Simulacrum`
