panic when more than one op with the same struct ident

[alexbatashev]

Comes from linkme crate:

---- ops::alu::tests::test_sema stdout ----
thread 'ops::alu::tests::test_sema' panicked at /home/alex/.cargo/registry/src/index.crates.io-6f17d22bba15001f/linkme-0.3.27/src/distributed_slice.rs:259:13:
duplicate #[distributed_slice] with name "ADDOP_METADATA"
stack backtrace:
   0: rust_begin_unwind
             at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/std/src/panicking.rs:645:5
   1: core::panicking::panic_fmt
             at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/core/src/panicking.rs:72:14
   2: linkme::distributed_slice::DistributedSlice<[T]>::static_slice
             at /home/alex/.cargo/registry/src/index.crates.io-6f17d22bba15001f/linkme-0.3.27/src/distributed_slice.rs:259:13
   3: <linkme::distributed_slice::DistributedSlice<[T]> as core::ops::deref::Deref>::deref
             at /home/alex/.cargo/registry/src/index.crates.io-6f17d22bba15001f/linkme-0.3.27/src/distributed_slice.rs:295:9
   4: tir_core::utils::op_dyn_cast
             at /home/alex/Projects/perf-toolbox/tir/core/src/utils.rs:59:17
   5: tir_backend::isema::conversion::convert_to_isema::{{closure}}
             at /home/alex/Projects/perf-toolbox/tir/backends/common/src/isema/conversion.rs:12:30
   6: tir_core::walkers::dfs_walk
             at /home/alex/Projects/perf-toolbox/tir/core/src/walkers.rs:24:9
   7: tir_backend::isema::conversion::convert_to_isema
             at /home/alex/Projects/perf-toolbox/tir/backends/common/src/isema/conversion.rs:11:5
   8: tir_riscv::ops::alu::tests::test_sema
             at ./src/ops/alu.rs:250:9
   9: tir_riscv::ops::alu::tests::test_sema::{{closure}}
             at ./src/ops/alu.rs:224:19
  10: core::ops::function::FnOnce::call_once
             at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/core/src/ops/function.rs:250:5
  11: core::ops::function::FnOnce::call_once
             at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.