[llvm] Run pre-merge build with -k 0 to ensure all tests runs (PR #84828)

[Mehdi Amini via llvm-commits]

joker-eph wrote:

It will continue to build all the targets it can build: if there is a test target that can run without libSupport it will get there eventually. But it can't build anything that depends on libSupport.

https://github.com/llvm/llvm-project/pull/84828