[lld] [ELF] Change Ctx::target to unique_ptr (PR #111260)

[Peter Smith via llvm-commits]

smithp35 wrote:

The specific change to the LLD output in the sanitizer build which I've reproduced locally is that the asan built lld uses 0xbebebebe for the alignment padding between the bti c b target which is disassembled to <unknown> whereas on a normal release build 0x0 gets used which is disassembled to <udf>.

If it is intentional that the padding value might change (undefined perhaps) then I can submit a patch to remove the <udf> part of the test. It isn't important what value the padding has.

https://github.com/llvm/llvm-project/pull/111260