Remove references to the old postopt pass

cranelift/codegen/src/timing.rs

@@ -55,7 +55,6 @@ define_passes! {
     flowgraph: "Control flow graph",
     domtree: "Dominator tree",
     loop_analysis: "Loop analysis",
-    postopt: "Post-legalization rewriting",
     preopt: "Pre-legalization rewriting",
     dce: "Dead code elimination",
     legalize: "Legalization",

cranelift/docs/testing.md

@@ -299,13 +299,6 @@ Test the preopt pass.
 The preopt pass is run on each function, and then results are run
 through filecheck.
 
-### `test postopt`
-
-Test the postopt pass.
-
-The postopt pass is run on each function, and then results are run
-through filecheck.
-
 ### `test compile`
 
 Test the whole code generation pipeline.