[clang] [mlir] [lld] [llvm] [flang] [ELF] Merge exportDynamic into versionId (PR #71272)

[Fangrui Song via cfe-commits]

MaskRay wrote:

Obsoleted by 255ea486085fca79d21eb0082594579abdbd89d0 (#72208).

In Bazel, `linkopts` on a `cc_library` target is propagated to an executable. If a cc_library specifies `--version-script`, with this patch the executable will export certain symbols. Breaking GNU compatibility is probably not great and #72208 is superior.

https://github.com/llvm/llvm-project/pull/71272