scons: make sure help is displayed if -h or --help is supplied even if we are not able to configure successfully and add more user friendly output for dependencies that are not found
scons: make sure help is displayed if -h or --help is supplied even if we are not able to configure successfully and add more user friendly output for dependencies that are not found

git-svn-id: 5adfda8227e14e59fd47d5bd9925a30df16fed74@1514 d397654b-2ff0-0310-9e29-ba003691a0f9

craigds/mapnik2,makinacorpus/mapnik2,makinacorpus/mapnik2,craigds/mapnik2,craigds/mapnik2,craigds/mapnik2,makinacorpus/mapnik2,makinacorpus/mapnik2