Zero bytes SSLEngine read with JDK 11

[veita]

JDK 11 changed behaviour of the SSLEngine#unwrap method which could result in zero bytes reads. As a result SSLUtil#read may return 0 which leads to errors.

jaffre/src/main/java/org/jaffre/ssl/SSLUtil.java

Line 362 in 6e83058

return l_iBytesAfter - l_iBytesBefore;