gnu: Add dfu-programmer

* gnu/packages/flashing-tools.scm (dfu-programmer): New variable.
* gnu/packages/patches/dfu-programmer-fix-libusb.patch: New patch.
* gnu-system.am (dist_patch_DATA): Add it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu: Move flashrom and avrdude to (gnu packages flashing-tools).

* gnu/packages/admin.scm (flashrom): Move this and...
* gnu/packages/avrdude.scm (avrdude): ... this to...
* gnu/packages/flashing-tools.scm: ... this. New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Adjust accordingly.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

Merge branch 'master' into core-updates

gnu: Add AVRDUDE

* gnu/packages/avrdude.scm: New file
* gnu-system.am (GNU_SYSTEM_MODULES): Add avrdude.scm
* gnu/packages/patches/avrdude-fix-libusb.patch: New patch.
* gnu-system.am (dist_patch_DATA): Add it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>