ci: Uprev Mesa with the uprev to Debian 12

The automatic uprev made with ci-uprev found two particular issues that require the attention of a maintainer.

With the uprev to Debian 12, the debian/x86_build-ming job has been turned off until a fix comes to Debian. So, the build image from Mesa has been put on hold, therefore virglrenderer's job debian/mingw32-x86_64 cannot continue. Consequently, we can apply Mesa's solution and put it on hold. Then, wait until the fix arrives at Debian.

Another change that affects us, is regarding the launcher of clang. Now it comes with a suffix of the LLVM release. This change helps in the coexistence of multiple versions, which used to be difficult in the past. That means, we need to change the binary name accordingly.

This merge request also absorbs !1137 (closed), about a change in the architectures naming convention, as a single merge request to uprev Mesa with all the required changes to do it.