[llvm] [llvm-lib] [Object] Use ECSYMBOLS section for ARM64EC importlib symbols. (PR #68328)

[Jacek Caban via llvm-commits]

cjacek wrote:

> For the test, I'm not entirely sure exactly which aspects of the test output would have been different without this change though.

The part that's changes in the test is 'Archive EC map' instead of 'Archive map'. The rest of the test just makes sure that the importlib is reasonable and it will be useful to see the difference that follow-up will make.

https://github.com/llvm/llvm-project/pull/68328