Rollup merge of #124712 - Enselic:deprecate-inline-threshold, r=pnkfelix

Deprecate no-op codegen option `-Cinline-threshold=...`

This deprecates `-Cinline-threshold` since using it has no effect. This has been the case since the new LLVM pass manager started being used, more than 2 years ago.

Recommend using `-Cllvm-args=--inline-threshold=...` instead.

Closes #89742 which is E-help-wanted.

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -120,7 +120,6 @@ pub struct ModuleConfig {
     pub vectorize_loop: bool,
     pub vectorize_slp: bool,
     pub merge_functions: bool,
-    pub inline_threshold: Option<u32>,
     pub emit_lifetime_markers: bool,
     pub llvm_plugins: Vec<String>,
 }
@@ -280,7 +279,6 @@ impl ModuleConfig {
                 }
             },
 
-            inline_threshold: sess.opts.cg.inline_threshold,
             emit_lifetime_markers: sess.emit_lifetime_markers(),
             llvm_plugins: if_regular!(sess.opts.unstable_opts.llvm_plugins.clone(), vec![]),
         }