Symbol visibility question

[Jeff Law]

Per Roland's suggestion here:

http://sourceware.org/ml/libc-alpha/2012-06/msg00207.html

I need to create a trivial little function that svc_{tcp,udp,unix} can 
use for failures.  Let's call it __svc_accept_failed.

That function needs to be visible to the svc_{tcp,udp,unix}.c files, but 
must not be visible outside glibc or sunrpc.

Unfortunately, I have found any glibc internals documentation on how to 
do this.  I see various libc_hidden_proto, libc_hidden_def macros, but 
no documentation on how to use them.

I'd like to get this wrapped up, so any advice/pointers would certainly 
be appreciated.

jeff