llvm12 & llvm16: update to build with llvmgold.so

[anphel31]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• [x] The toolchain has been rebuilt successfully (or no changes were made to it)
• [x] The toolchain/worker package manifests are up-to-date
• [x] Any updated packages successfully build (or no packages were changed)
• [x] Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• [x] Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• [x] All package sources are available
• [x] cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• [x] LICENSE-MAP files are up-to-date (./SPECS/LICENSES-AND-NOTICES/data/licenses.json, ./SPECS/LICENSES-AND-NOTICES/LICENSES-MAP.md, ./SPECS/LICENSES-AND-NOTICES/LICENSE-EXCEPTIONS.PHOTON)
• [x] All source files have up-to-date hashes in the *.signatures.json files
• [x] sudo make go-tidy-all and sudo make go-test-coverage pass
• [x] Documentation has been updated to match any changes to the build system
• [ ] Ready to merge

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Summary

What does the PR accomplish, why was it needed? Update llvm to build the LLVM gold plugin LLVMgold.so to support link time optimization.

Change Log

• Change llvm12 to build LLVMgold.so
• Change llvm16 to build LLVMgold.so

Does this affect the toolchain?

NO

Associated issues

• #6999

Test Methodology

• Pipeline build id: https://dev.azure.com/mariner-org/mariner/_build/results?buildId=542377&view=results

[anphel31]

Waiting for approval to backport this fix