Log used native library by netty-tcnative

Motivation:

As netty-tcnative can be build against different native libraries and versions we should log the used one.

Modifications:

Log the used native library after netty-tcnative was loaded.

Result:

Easier to understand what native SSL library was used.

handler/src/main/java/io/netty/handler/ssl/OpenSsl.java

@@ -112,6 +112,8 @@ public final class OpenSsl {
         UNAVAILABILITY_CAUSE = cause;
 
         if (cause == null) {
+            logger.debug("netty-tcnative using native library: {}", SSL.versionString());
+
             final Set<String> availableOpenSslCipherSuites = new LinkedHashSet<String>(128);
             boolean supportsKeyManagerFactory = false;
             boolean useKeyManagerFactory = false;