Make regparm-module-flag.rs a minicore test

Author: winstonallo

tests/assembly-llvm/regparm-module-flag.rs

@@ -1,10 +1,14 @@
+//@ add-core-stubs
 //@ assembly-output: emit-asm
-//@ compile-flags: -O -Zregparm=3 -Cunsafe-allow-abi-mismatch=regparm
+//@ compile-flags: -O -Zregparm=3
 //@ only-x86
 
+#![feature(no_core)]
+#![no_std]
+#![no_core]
 #![crate_type = "lib"]
 
-use std::ffi::c_void;
+use minicore::*;
 
 unsafe extern "C" {
     fn memset(p: *mut c_void, val: i32, len: usize) -> *mut c_void;