[llvm] [SPIR-V] Sort basic blocks to match the SPIR-V spec (PR #102929)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

Waiting on the presubmit to finish, and will merge if fine.
(There is one failure upstream on the parser_overflow test, which is unrelated)

https://github.com/llvm/llvm-project/pull/102929