Rollup merge of #90001 - Fearyncess:master, r=alexcrichton

Rollup merge of #90001 - Fearyncess:master, r=alexcrichton

Make rlib metadata strip works with MIPSr6 architecture

Because MIPSr6 has many differences with previous MIPSr2 arch, the previous rlib metadata stripping code in `rustc_codegen_ssa` is only for MIPSr2/r3/r5 (which share the same elf e_flags).

This commit fixed this problem. It makes `rustc_codegen_ssa` happy when compiling rustc for MIPSr6 target or hosts.

e_flags REF: https://github.com/llvm/llvm-project/blob/e356027016c6365b3d8924f54c33e2c63d931492/llvm/include/llvm/BinaryFormat/ELF.h#L562