Match wasm32-unknown-unknown ABI with clang

compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs

@@ -17,16 +17,6 @@ pub fn target() -> Target {
     let mut options = wasm_base::options();
     options.os = "unknown".into();
 
-    // This is a default for backwards-compatibility with the original
-    // definition of this target oh-so-long-ago. Once the "wasm" ABI is
-    // stable and the wasm-bindgen project has switched to using it then there's
-    // no need for this and it can be removed.
-    //
-    // Currently this is the reason that this target's ABI is mismatched with
-    // clang's ABI. This means that, in the limit, you can't merge C and Rust
-    // code on this target due to this ABI mismatch.
-    options.default_adjusted_cabi = Some(Abi::Wasm);
-
     options.add_pre_link_args(
         LinkerFlavor::WasmLld(Cc::No),
         &[