[llvm] [FinalizelSel] Re-scan the MachineFunction if we insert a new MBB by custom insertion (PR #96046)

[Craig Topper via llvm-commits]

topperc wrote:

If I'm reading the failing test right, we have a select before a call to memset and a select after the call. We merge them into a single control flow change. Is that really something we should be doing?

We already abort the scan for
```
    if (SequenceMBBI->hasUnmodeledSideEffects() ||                               
        SequenceMBBI->mayLoadOrStore() ||                                        
        SequenceMBBI->usesCustomInsertionHook())                                 
      break;   
```

Should call be included?

https://github.com/llvm/llvm-project/pull/96046