[lld] [LLD][AArch64] Mark .plt with PURECODE flag if all input sections also have it (PR #132224)

[Csanád Hajdú via llvm-commits]

Il-Capitano wrote:

I had some concern about the performance impact of looping through all input sections when creating the `.plt` section, so I did some measurements of building Clang with `-mexecute-only -ffunction-sections` on an AArch64 machine (I verified that the final binary has the correct flags set).

I couldn't measure any time difference in the linking step between the old and new versions, it was within noise. So I don't think performance of the loop is a concern. In the common, non-execute-only case, short circuiting in `all_of` should also prevent any noticeable time difference.

https://github.com/llvm/llvm-project/pull/132224