[lld] [LLD][COFF] Always locate the IAT at the beginning of the .rdata section and align its size to 4KB on ARM64EC. (PR #107588)

[Jacek Caban via llvm-commits]

cjacek wrote:

One difference from MSVC's link.exe is that, if .rdata is merged into another section, MSVC places the IATs within that section, whereas this PR hardcodes the .rdata placement. While it might be possible to replicate MSVC's behavior, this would likely require calling assignOutputSectionIndices() earlier.

https://github.com/llvm/llvm-project/pull/107588