hg: jdk/sandbox: Extract common code in a superclass.

[magnus.ihse.bursie at oracle.com]

Changeset: 531849651296
Author:    ihse
Date:      2020-06-02 13:23 +0200
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/531849651296

Extract common code in a superclass.

+ make/src/classes/build/tools/pandocfilter/PandocFilter.java
! make/src/classes/build/tools/pandocfilter/PandocManPageHtmlFilter.java
! make/src/classes/build/tools/pandocfilter/PandocManPageTroffFilter.java