Remove the wasmtime wasm2obj command (#3301)

* Remove the `wasmtime wasm2obj` command

This commit removes the `wasm2obj` subcommand of the `wasmtime` CLI.
This subcommand has a very long history and dates back quite far. While
it's existed, however, it's never been documented in terms of the output
it's produced. AFAIK it's only ever been used for debugging to see the
machine code output of Wasmtime on some modules. With recent changes to
the module serialization output the output of `wasmtime compile`, the
`*.cwasm` file, is now a native ELF file which can be fed to standard
tools like `objdump`. Consequently I dont think there's any remaining
need to keep `wasm2obj` around itself, so this commit removes the
subcommand.

* More code to delete

* Try to fix debuginfo tests

tests/all/debug/obj.rs

@@ -3,25 +3,24 @@ use std::fs::File;
 use std::io::Write;
 use std::path::Path;
 use target_lexicon::Triple;
-use wasmtime::Strategy;
-use wasmtime_cli::compile_to_obj;
+use wasmtime::{Config, Engine, Module};
 
 pub fn compile_cranelift(
     wasm: &[u8],
     target: Option<Triple>,
     output: impl AsRef<Path>,
 ) -> Result<()> {
-    let obj = compile_to_obj(
-        wasm,
-        target.as_ref(),
-        Strategy::Cranelift,
-        false,
-        wasmtime::OptLevel::None,
-        true,
-    )?;
+    let mut config = Config::new();
+    config.debug_info(true);
+    if let Some(target) = target {
+        config.target(&target.to_string())?;
+    }
+    let engine = Engine::new(&config)?;
+    let module = Module::new(&engine, wasm)?;
+    let bytes = module.serialize()?;
 
     let mut file = File::create(output).context("failed to create object file")?;
-    file.write_all(&obj)
+    file.write_all(&bytes)
         .context("failed to write object file")?;
 
     Ok(())