graphics/simpleviewer: the port had been updated to version 3.1.9
Employ the ?dummy=/ trick in the download URL so that the standard
DISTNAME works and we can drop DIST_SUBDIR.
- Update `graphics/simpleviewer' to version 2.88
- Add missing USE_XORG components as reported by `stage-qa'
- Project had moved from SourceForge to Bitbucket