TLSProxy/Proxy.pm: straighten inner loop termination logic.

Original condition was susceptible to race condition...

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5933)
1 file changed