doc: use /* ... */ comments in code examples

Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1956)

doc/man3/BIO_s_bio.pod

@@ -144,7 +144,7 @@ without having to go through the SSL-interface.
  ...
  BIO_new_bio_pair(&internal_bio, 0, &network_bio, 0);
  SSL_set_bio(ssl, internal_bio, internal_bio);
- SSL_operations(); //e.g SSL_read and SSL_write
+ SSL_operations(); /* e.g SSL_read and SSL_write */
  ...
 
  application |   TLS-engine

doc/man3/CRYPTO_THREAD_run_once.pod

@@ -149,9 +149,9 @@ You can find out if OpenSSL was configured with thread support:
 
  #include <openssl/opensslconf.h>
  #if defined(OPENSSL_THREADS)
-     // thread support enabled
+     /* thread support enabled */
  #else
-     // no thread support
+     /* no thread support */
  #endif
 
 =head1 SEE ALSO