eclipse: switch to officially mirrored download URLs

That is, replace all mirror specific URLs with the generic form:

  http://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/path/to/file

* r=1 auto-redirects to best mirror
* nf=1 returns HTTP 404 if there is no file, instead of HTML data

It's documented here:

  http://wiki.eclipse.org/IT_Infrastructure_Doc#Use_mirror_sites.2Fsee_which_mirrors_are_mirroring_my_files.3F

All URLs are tested (they work).