Rollup merge of #107711 - calebzulawski:movbe, r=pnkfelix

Stabilize movbe target feature

Almost all "old" x86 target features are stable.  As far as I can tell, these are the last two unstable features in the `x86-64-v2` or `x86-64-v3` microarchitecture levels, so I'm not sure if it was an oversight or if they're still unstable for a reason (see #106323 for `f16c`).

Note that this only stabilizes the target features, and not the intrinsics.

cc ```@Amanieu```

r? ```@rust-lang/lang```

Author: matthiaskrgr