Fix HiPE debug lock checking on OS X 64bit

Position-independent code is mandatory on OS X. We use r11 as an intermediate register to fill
BIF_P->hipe.bif_callee. This fixes the following error when doing `make debug FLAVOR=smp`:

```
clang -cc1as: fatal error: error in backend: 32-bit absolute addressing is not supported in 64-bit mode
```