[llvm] [llvm-objcopy] Explain that strip-preserve-atime.test fails with Crowdstrike (PR #145783)

[Ross Kirsling via llvm-commits]

rkirsling wrote:

(I'd ask for this to be merged, but I figure it'll be a good way to test out my ability to do so myself once my commit access invite arrives.)

https://github.com/llvm/llvm-project/pull/145783