Bug #1022519 - graphics.xsl fails with error about no X11 server

Bug #1022519 - graphics.xsl fails with error about no X11 server

Problem
  Current stylesheets fail when trying to generate output under
  the following conditions:

    - Linux/Unix environment
    - no X server running
    - document contains graphics
    - use.extensions enabled

  This makes it impossible to try to do extensions-enabled
  automated transformations (e.g., nightly doc builds) in a server
  environment.

Cause
  Certain methods in the DocBook "ImageIntrisics" extensions class
  rely on the Java AWT library, which by default expects a running
  X server.

Fix
  Both the Saxon and Xalan2 versions of the extensions now set the
  "java.awt.headless" Java 1.4 system property to true. That
  property tells Java to continue processing AWT-based code even
  if no running X server is found.

  The property is set at the beginning of the constructor for the
  ImageIntrinsics class.

Affects
  This change only affects transformations using Saxon or Xalan2
  under the conditions:

    - Linux/Unix environment
    - no X server running
    - document contains graphics
    - use.extensions enabled