hg: jdk/sandbox: 8180019: javadoc should treat failure to access URL as an error, not a warning.

[chris.hegarty at oracle.com]

Changeset: 7e57d42b5eeb
Author:    ksrini
Date:      2017-11-21 13:17 -0800
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/7e57d42b5eeb

8180019: javadoc should treat failure to access URL as an error, not a warning.
Reviewed-by: jjg

! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/Extern.java
! test/langtools/jdk/javadoc/doclet/testLinkOption/TestBadLinkOption.java
! test/langtools/jdk/javadoc/doclet/testLinkOption/TestNewLineInLink.java