[lld] [lld] Mark target section as code section when merging code sections into a data section. (PR #72030)

[Jacek Caban via llvm-commits]

cjacek wrote:

I created #72138 fixing the problem with gap fills filling uninitialized data chunks and rebased this PR on top of that.

https://github.com/llvm/llvm-project/pull/72030