Rollup merge of rust-lang#110490 - jyn514:bump-llvm, r=nikic

Bump `download-ci-llvm-stamp` for loong support

This was missed in rust-lang#96971 and resulted in the LLVM we cache in CI being different from the one built locally. We didn't catch it because nothing tested the loong support.

Fixes rust-lang#110474.

r? `@nikic`

Author: GuillaumeGomez

src/bootstrap/download-ci-llvm-stamp

@@ -1,4 +1,4 @@
 Change this file to make users of the `download-ci-llvm` configuration download
 a new version of LLVM from CI, even if the LLVM submodule hasn’t changed.
 
-Last change is for: https://github.com/rust-lang/rust/pull/109373
+Last change is for: https://github.com/rust-lang/rust/pull/96971