Remove pass initialization code

This is no longer necessary with the new pass manager.

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1814,8 +1814,6 @@ extern "C" {
     /// Creates a legacy pass manager -- only used for final codegen.
     pub fn LLVMCreatePassManager<'a>() -> &'a mut PassManager<'a>;
 
-    pub fn LLVMInitializePasses();
-
     pub fn LLVMTimeTraceProfilerInitialize();
 
     pub fn LLVMTimeTraceProfilerFinishThread();

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -120,8 +120,6 @@ unsafe fn configure_llvm(sess: &Session) {
         llvm::LLVMTimeTraceProfilerInitialize();
     }
 
-    llvm::LLVMInitializePasses();
-
     rustc_llvm::initialize_available_targets();
 
     llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr());