perf: cranelift-codegen-meta: less llvm-lines: vec![...] -> &[...]

[dishmaker]

change: -4.2 % less llvm lines

Before:
  Lines                 Copies              Function name
  -----                 ------              -------------
  187113                4294                (TOTAL)
   16739 (8.9%,  8.9%)     1 (0.0%,  0.0%)  cranelift_codegen_meta[5b669ca35bdaf383]::shared::instructions::define
    3772 (2.0%, 11.0%)     1 (0.0%,  0.0%)  <cranelift_codegen_meta[5b669ca35bdaf383]::gen_isle::NumericOp>::ops_for_type


After:
Lines                 Copies              Function name
  -----                 ------              -------------
  179088                4286                (TOTAL)
   10042 (5.6%,  5.6%)     1 (0.0%,  0.0%)  cranelift_codegen_meta[5b669ca35bdaf383]::shared::instructions::define
    3772 (2.1%,  7.7%)     1 (0.0%,  0.0%)  <cranelift_codegen_meta[5b669ca35bdaf383]::gen_isle::NumericOp>::ops_for_type