[lld] [LLD][COFF] Move delay IAT into its own .didat section. (PR #137100)

[via llvm-commits]

kkent030315 wrote:

@mstorsjo I like this PR, and would like to see get this merged. Based on my previous comments about how MS link works I think the right direction for this would be something like:

- Adding /didatownsection flag
- Under the condition (if the flag on) modify the didat section to writable and don't perform merge to RDATA
- Adding tests to verify that verifies the all delay load datas are in didat section (so tests diff in this PR would not be required)

I am actually not in favor of doing these by default and unconditionally as that is not backward-compatible. What do you think?

https://github.com/llvm/llvm-project/pull/137100