linuxthreads.old: only declare __pthread_xxx funcs hidden inside of libpthread

These stubs get used in libc as forwarding funcs, so we don't want them
labeled as hidden.  Otherwise, attempting to use them in other libraries
(like libdl) will result in references to symbols that only libpthread
provides.  Such as:
	/usr/bin/python2.6: can't resolve symbol '__pthread_mutex_lock' in lib '/lib/libdl.so.0'.

This also brings the old code in line with the newer linuxthreads.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

libpthread/linuxthreads.old/internals.h

@@ -506,11 +506,13 @@ extern void __pthread_wait_for_restart_signal(pthread_descr self);
 extern void (*__pthread_restart)(pthread_descr);
 extern void (*__pthread_suspend)(pthread_descr);
 
+#if defined NOT_IN_libc && defined IS_IN_libpthread
 extern __typeof(pthread_mutex_init) __pthread_mutex_init attribute_hidden;
 extern __typeof(pthread_mutex_destroy) __pthread_mutex_destroy attribute_hidden;
 extern __typeof(pthread_mutex_lock) __pthread_mutex_lock attribute_hidden;
 extern __typeof(pthread_mutex_trylock) __pthread_mutex_trylock attribute_hidden;
 extern __typeof(pthread_mutex_unlock) __pthread_mutex_attribute_hidden;
+#endif
 
 /* Prototypes for some of the new semaphore functions.  */
 extern int __new_sem_post (sem_t * sem);