[compiler-rt] [libFuzzer] always install signal handler with SA_ONSTACK (PR #147422)

[Sebastian Poeplau via llvm-commits]

sebastianpoeplau wrote:

Like I said on the old Phabricator discussion, I think this is good to go in. However, I don't have rights to formally approve or merge :man_shrugging: 

https://github.com/llvm/llvm-project/pull/147422