Clarify 'possible LibreSSL bug'

These test fail by default because of lack of PSK support in LibreSSL's
TLSv1.3 stack. They do work with SslOptions::NO_TLSV1_3 but it seems
preferable to keep ignoring the tests until they are properly supported.

openssl/src/ssl/test/mod.rs

@@ -1023,7 +1023,9 @@ fn idle_session() {
     assert!(ssl.session().is_none());
 }
 
-/// possible LibreSSL bug since 3.2.1
+/// LibreSSL 3.2.1 enabled TLSv1.3 by default for clients and sessions do
+/// not work due to lack of PSK support. The test passes with NO_TLSV1_3,
+/// but let's ignore it until LibreSSL supports it out of the box.
 #[test]
 #[cfg_attr(libressl321, ignore)]
 fn active_session() {
@@ -1081,7 +1083,9 @@ fn status_callbacks() {
     assert!(CALLED_BACK_CLIENT.load(Ordering::SeqCst));
 }
 
-/// possible LibreSSL bug since 3.2.1
+/// LibreSSL 3.2.1 enabled TLSv1.3 by default for clients and sessions do
+/// not work due to lack of PSK support. The test passes with NO_TLSV1_3,
+/// but let's ignore it until LibreSSL supports it out of the box.
 #[test]
 #[cfg_attr(libressl321, ignore)]
 fn new_session_callback() {
@@ -1106,7 +1110,9 @@ fn new_session_callback() {
     assert!(CALLED_BACK.load(Ordering::SeqCst));
 }
 
-/// possible LibreSSL bug since 3.2.1
+/// LibreSSL 3.2.1 enabled TLSv1.3 by default for clients and sessions do
+/// not work due to lack of PSK support. The test passes with NO_TLSV1_3,
+/// but let's ignore it until LibreSSL supports it out of the box.
 #[test]
 #[cfg_attr(libressl321, ignore)]
 fn new_session_callback_swapped_ctx() {