Fix personality_fn within the compiler_builtins

compiler_builtins may not have any unwinding within it to link correctly. This is notoriously
finicky, and this small piece of change removes yet another case where personality function
happens to get introduced.

Side note: I do remember solving the exact same thing before. I wonder why it has reappered...

src/libcompiler_builtins/lib.rs

@@ -402,15 +402,16 @@ pub mod reimpls {
     }
 
     trait AbsExt: Sized {
-        fn uabs(self) -> u128 {
-            self.iabs() as u128
-        }
+        fn uabs(self) -> u128;
         fn iabs(self) -> i128;
     }
 
     impl AbsExt for i128 {
+        fn uabs(self) -> u128 {
+            self.iabs() as u128
+        }
         fn iabs(self) -> i128 {
-            let s = self >> 127;
+            let s = self.wrapping_shr(127);
             ((self ^ s).wrapping_sub(s))
         }
     }