RFR: 8180019: javadoc should treat failure to access URL as an error, not a warning.

[Kumar Srinivasan]

Hello,

Please review this simple fix for [1], webrev at [2].

Thanks
Kumar

[1] https://bugs.openjdk.java.net/browse/JDK-8180019
[2] http://cr.openjdk.java.net/~ksrini/8180019/webrev.00/