hg: jdk/sandbox: 8243113: Always identify version of javadoc used to generate docs

[chris.hegarty at oracle.com]

Changeset: 6629aa057963
Author:    jjg
Date:      2020-06-17 09:24 -0700
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/6629aa057963

8243113: Always identify version of javadoc used to generate docs
Reviewed-by: prappo

! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Head.java
! test/langtools/jdk/javadoc/doclet/testGeneratedBy/TestGeneratedBy.java
! test/langtools/jdk/javadoc/doclet/testHeadTag/TestHeadTag.java