Redirect binutils package download requests to OSDN.net

Redirect binutils package download requests to OSDN.net

* mingw32/mingw32-binutils.xml (download-host): Relocate to osdn.net
(binutils-bin, binutils-dev): Prune all release references other than
those for version 2.28-1; these earlier releases will remain available
on SourceForge.net, but are not scheduled for relocation to OSDN.net
(binutils-info, binutils-man, binutils-lang): Likewise.
(binutils-2.24-1-doc): Retain effectively empty virtual package;
vacate its dependency list; prune all other version references.
* common/issue.log mingw32/issue.log: Update accordingly.