Linker is still invoked with target BPF

[LucasSte]

When we compile a project for the SBF target, we still invoke the linker, assuming the BPF target.

Them seems to be related to the following line:

rust/compiler/rustc_codegen_ssa/src/back/metadata.rs

Line 214 in 696ef74

"sbf" => Architecture::Bpf,

However, changing it to Architecture::Sbf crashes the linker, as we try to put together files compiled for both the BPF and the SBF target.

We are either invoking the compiler for both targets or writing the incorrect architecture in the file header.

[LucasSte]

We are still writing EM_BPF in the ELF object: https://github.com/anza-xyz/llvm-project/blob/bda98722f7b7806d037185b4891b9419feee720c/llvm/lib/Target/SBF/MCTargetDesc/SBFELFObjectWriter.cpp#L53