Remove aapcs_on_arm mistake

Author: AaronKutch

src/int/mul.rs

@@ -104,7 +104,6 @@ intrinsics! {
         a.mul(b)
     }
 
-    #[aapcs_on_arm]
     pub extern "C" fn __multi3(a: i128, b: i128) -> i128 {
         a.mul(b)
     }