Fix a number of warnings cropping up on nightly Rust (#2767)

Various small issues here and there, nothing major

cranelift/wasm/src/code_translator.rs

@@ -64,11 +64,11 @@
 //! 32X4 and 64X2 types from CLIF and instead have a single V128 type.
 //!
 //! For further background see also:
-//!   https://github.com/bytecodealliance/wasmtime/issues/1147
+//!   <https://github.com/bytecodealliance/wasmtime/issues/1147>
 //!     ("Too many raw_bitcasts in SIMD code")
-//!   https://github.com/bytecodealliance/cranelift/pull/1251
+//!   <https://github.com/bytecodealliance/cranelift/pull/1251>
 //!     ("Add X128 type to represent WebAssembly's V128 type")
-//!   https://github.com/bytecodealliance/cranelift/pull/1236
+//!   <https://github.com/bytecodealliance/cranelift/pull/1236>
 //!     ("Relax verification to allow I8X16 to act as a default vector type")
 
 use super::{hash_map, HashMap};

cranelift/wasm/src/sections_translator.rs

@@ -110,8 +110,7 @@ pub fn parse_type_section<'a>(
     for entry in types {
         match entry? {
             TypeDef::Func(wasm_func_ty) => {
-                let mut sig =
-                    Signature::new(ModuleEnvironment::target_config(environ).default_call_conv);
+                let mut sig = Signature::new(environ.target_config().default_call_conv);
                 sig.params.extend(wasm_func_ty.params.iter().map(|ty| {
                     let cret_arg: ir::Type = type_to_type(*ty, environ)
                         .expect("only numeric types are supported in function signatures");