Revert "Don't duplicate check_abi()"

This reverts commit 1c7d7471da.

src/helpers.rs

@@ -169,7 +169,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let this = self.eval_context_mut();
         let param_env = ty::ParamEnv::reveal_all(); // in Miri this is always the param_env we use... and this.param_env is private.
         let callee_abi = f.ty(*this.tcx, param_env).fn_sig(*this.tcx).abi();
-        check_abi(caller_abi, callee_abi)?;
+        if callee_abi != caller_abi {
+            throw_ub_format!("calling a function with ABI {} using caller ABI {}", callee_abi.name(), caller_abi.name())
+        }
 
         // Push frame.
         let mir = &*this.load_mir(f.def, None)?;