pthread_{attr_,}{s,g}etaffinity: cleanup symbol names

fixes typo in a1ee5b32fc698297149c770417354441ee62701e which forgot to
rename __pthread_attr_getaffinity_np to pthread_attr_getaffinity_np.
Thanks to Andre DRASZIK for mentioning my omission.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libpthread/nptl/sysdeps/unix/sysv/linux/pthread_attr_getaffinity.c

@@ -26,7 +26,7 @@
 
 
 int
-__pthread_attr_getaffinity_np(const pthread_attr_t *attr, size_t cpusetsize,
+pthread_attr_getaffinity_np(const pthread_attr_t *attr, size_t cpusetsize,
 				cpu_set_t *cpuset)
 {
   const struct pthread_attr *iattr;