[llvm] [VPlan] Move addExplicitVectorLength to tryToBuildVPlanWithVPRecipes (PR #166164)

[Luke Lau via llvm-commits]

lukel97 wrote:

I've moved optimizeMasksToEVL later so it should be the last optimization now before costing in 5344cc9e9817b1fed1b226df4fbe50dcd1aeb1d6. Since I noticed that in #149706 narrowInterleaveRecipes will be moved earlier so making sure optimizeMasksToEVL runs after it means it shouldn't need to worry about EVL recipes.

https://github.com/llvm/llvm-project/pull/166164