[compiler-rt] [sanitizer_common][PowerPC64] Fix internal_clone() error handling (PR #99908)

[Chen Zheng via llvm-commits]

================
@@ -1630,13 +1630,22 @@ uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
       "sc\n\t"
 
       /* Return to parent */
+      "0:\n\t"
+      "neg %0,3\n\t"
+      "b 2f\n\t"
       "1:\n\t"
-      "mr %0, 3\n\t"
+      "mr %0,3\n\t"
+      "2:\n\t"
----------------
chenzheng1030 wrote:

```
      "0:\n\t"
      "neg 3,3\n\t"
      "1:\n\t"
      "mr %0,3\n\t"
```

nit: Does this looks better than the original one?

https://github.com/llvm/llvm-project/pull/99908