Auto merge of #1599 - YangKeao:macos, r=gnzlbg

add pthread_getname_np for mac os

In macos's `pthread.h`

```c
/*SPI to set and get pthread name*/
__API_AVAILABLE(macos(10.6), ios(3.2))
int	pthread_getname_np(pthread_t,char*,size_t);

__API_AVAILABLE(macos(10.6), ios(3.2))
int	pthread_setname_np(const char*);
```

I believe `pthread_getname_np` is usable in macos after 10.6.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>