gnu: Update URLs for sourceforge.net.

gnu: Update URLs for sourceforge.net.

* gnu/packages/admin.scm: Update URLs pointing to sourceforge.net.
* gnu/packages/audacity.scm: Likewise.
* gnu/packages/audio.scm: Likewise.
* gnu/packages/bioinformatics.scm: Likewise.
* gnu/packages/boost.scm: Likewise.
* gnu/packages/cdrom.scm: Likewise.
* gnu/packages/code.scm: Likewise.
* gnu/packages/compression.scm: Likewise.
* gnu/packages/cups.scm: Likewise.
* gnu/packages/djvu.scm: Likewise.
* gnu/packages/docbook.scm: Likewise.
* gnu/packages/documentation.scm: Likewise.
* gnu/packages/flashing-tools.scm: Likewise.
* gnu/packages/fonts.scm: Likewise.
* gnu/packages/fontutils.scm: Likewise.
* gnu/packages/games.scm: Likewise.
* gnu/packages/ghostscript.scm: Likewise.
* gnu/packages/gl.scm: Likewise.
* gnu/packages/gnucash.scm: Likewise.
* gnu/packages/graphviz.scm: Likewise.
* gnu/packages/image.scm: Likewise.
* gnu/packages/libreoffice.scm: Likewise.
* gnu/packages/libusb.scm: Likewise.
* gnu/packages/linux.scm: Likewise.
* gnu/packages/lirc.scm: Likewise.
* gnu/packages/maths.scm: Likewise.
* gnu/packages/mcrypt.scm: Likewise.
* gnu/packages/mp3.scm: Likewise.
* gnu/packages/music.scm: Likewise.
* gnu/packages/networking.scm: Likewise.
* gnu/packages/onc-rpc.scm: Likewise.
* gnu/packages/password-utils.scm: Likewise.
* gnu/packages/pdf.scm: Likewise.
* gnu/packages/perl.scm: Likewise.
* gnu/packages/photo.scm: Likewise.
* gnu/packages/popt.scm: Likewise.
* gnu/packages/python.scm: Likewise.
* gnu/packages/rdesktop.scm: Likewise.
* gnu/packages/screen.scm: Likewise.
* gnu/packages/swig.scm: Likewise.
* gnu/packages/tcl.scm: Likewise.
* gnu/packages/version-control.scm: Likewise.
* gnu/packages/video.scm: Likewise.
* gnu/packages/w3m.scm: Likewise.
* gnu/packages/web.scm: Likewise.
* gnu/packages/wm.scm: Likewise.
* gnu/packages/xdisorg.scm: Likewise.
* gnu/packages/xml.scm: Likewise.