imgdbug.h ins included in canvs under some debugging flags
but that header comes from
http://billbaxter.com/projects/imdebug/
and is nowhere to be found in our source. the original project
has been dead for a long while.. the last 'news' was that it was
migrating to the now defunc 'berlios' hosting site.

Change-Id: Idd030164f4ef0b28973530df69323cb952e99169
Reviewed-on: https://gerrit.libreoffice.org/17655Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>