NPTL: remove attribute_protected from function

This fixes a linking error with f.e. Kodi. Code behaves like
glibc now.

libpthread/nptl/pthread_key_create.c

@@ -22,7 +22,6 @@
 
 
 int
-attribute_protected
 __pthread_key_create (
      pthread_key_t *key,
      void (*destr) (void *))