Add FileCheck to move_arg.rs

Author: Shunpoco

tests/mir-opt/copy-prop/move_arg.rs

@@ -1,10 +1,13 @@
-// skip-filecheck
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 // Test that we do not move multiple times from the same local.
 //@ test-mir-pass: CopyProp
 
 // EMIT_MIR move_arg.f.CopyProp.diff
 pub fn f<T: Copy>(a: T) {
+    // CHECK-LABEL: fn f(
+    // CHECK: debug a => [[a:_.*]];
+    // CHECK: debug b => [[a]];
+    // CHECK: g::<T>(copy [[a]], copy [[a]])
     let b = a;
     g(a, b);
 }