[llvm] [llvm] Fix test breakage in Vectorize/VPlanVerifierTest.cpp (PR #140079)

[Jonathan Thackray via llvm-commits]

jthackray wrote:

This is breaking my builds (and probably other people's too) so I'm going to merge this now, as it's very low risk and fixes the issue.

https://github.com/llvm/llvm-project/pull/140079