[llvm] Run delta-pass with child process (PR #87647)

[John Regehr via llvm-commits]

regehr wrote:

> But how often is this actually happening? Fixing crashes on some unhandled IR is easy, and I can't recall ever encountering a reduction crashing

I only have my own experience to draw on. llvm-reduce crashing out before it can reduce something for me has happened a number of times, and this has been frustrating.

if you want to block this patch then I guess block the patch, but it seems simple and low cost and it solves an actual problem that has happened to me, and I assume to others. I don't see the problem here.

https://github.com/llvm/llvm-project/pull/87647