1fab0fc4a2
Remove legacy PM leftovers This drops two leftovers of legacy PM usage: * We don't need to initialize passes anymore. * The pass listing was still using legacy PM passes. Replace it with the corresponding new PM listing.
The codegen crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.