package/wiringpi: remove

The author has completely ripped off the git tree, so the sources
are no longer available, with that message:
    "Please look for alternatives for wiringPi"

And indeed there is a better alternative, using the kernel GPIO
subsystem and drivers.

Note that queezelite looses that functionality now, but upstream
squeezelite has done changes to do without wiringpi (hint for an
upgrade?).

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Peter Seiderer <ps.report@gmx.net>
Cc: Hiroshi Kawashima <kei-k@ca2.so-net.ne.jp>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>