[lld] [lld][ELF] Add armeb support when incoming bc is arm big endian (PR #72604)

[Fangrui Song via llvm-commits]

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+; REQUIRES: arm
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MaskRay wrote:

See the tests I added in abd80ecf6ed8f013b8c78fb00a2637dfc81e50cb . The comment convention is like `;; Test we can infer the e_machine value EM_RISCV from a bitcode file.`

(Double `;` to make comments oustanding from RUN/CHECK)

thumb needs to be tested as well.

https://github.com/llvm/llvm-project/pull/72604