Revision 7610

merge curl_download into Rpmdrake::edit_urpm_sources

rationale:
- it's its only user
- it has nothing to do with curl since 2008
  (and old XS curl code wasn't used anymore since 2003-05-12 when gurpm*
  stuff was merged in urpmi/gurpm*, grpmi/grpm.pl itself being killed on
  2004-01-21)
- gc was lazy