[llvm] [ARM][ConstantIslands] Correct MinNoSplitDisp calculation (PR #114590)

[David Green via llvm-commits]

davemgreen wrote:

It has been a while since I looked into the constant island pass, but this sounds OK. As you mention this should only kick in when we are already 15 iterations in, so is aiming to converge quickly at the expense of optimality. Did you run any checks (the llvm-test-suite or a boot strap), that can check we don't iterate for a long time now? Thanks.

https://github.com/llvm/llvm-project/pull/114590