TODO: remove the task for running external processes in gpiomon

TODO: remove the task for running external processes in gpiomon

This functionality can be achieved with a shell oneliner, for example:

  gpiomon --line-buffered --format="%o %e" 0 0 | while read line; \
						do cut -d" " -f2; done

There's no need to add this to the program. It would make the code
much more complicated without any real benefit.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>