Update graphics/libgeotiff to 1.5.1
- Bump PORTREVISION of dependent ports for shlib change
Changes: https://github.com/OSGeo/libgeotiff/blob/master/libgeotiff/NEWS
https://lists.osgeo.org/pipermail/geotiff/2019-March/000861.html https://lists.osgeo.org/pipermail/geotiff/2019-March/000862.html