PlatformDependent#getClassLoader fails in restrictive classloader environment

Motivation:
https://github.com/netty/netty/pull/6042 only addressed PlatformDependent#getSystemClassLoader but getClassLoader is also called in an optional manner in some common code paths but fails to catch a general enough exception to continue working.

Modifications:
- Calls to getClassLoader which can continue if results fail should catch Throwable

Result:
More resilient code in the presense of restrictive class loaders.
Fixes https://github.com/netty/netty/issues/6246.

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

@@ -135,7 +135,7 @@ public class ReferenceCountedOpenSslEngine extends SSLEngine implements Referenc
                 @SuppressWarnings({ "rawtypes", "unused" })
                 List serverNames = (List) getServerNamesMethod.invoke(parameters);
                 setServerNamesMethod.invoke(parameters, Collections.emptyList());
-            } catch (Throwable ingore) {
+            } catch (Throwable ignore) {
                 sniHostNameClass = null;
                 getAsciiNameMethod = null;
                 getServerNamesMethod = null;

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

@@ -854,8 +854,9 @@ public class SslHandler extends ByteToMessageDecoder implements ChannelOutboundH
                             && "com.sun.nio.sctp.SctpChannel".equals(clazz.getSuperclass().getName())) {
                         return true;
                     }
-                } catch (ClassNotFoundException e) {
-                    // This should not happen just ignore
+                } catch (Throwable cause) {
+                    logger.debug("Unexpected exception while loading class {} classname {}",
+                                 getClass(), classname, cause);
                 }
             }
         }