Currently, mraa_init is called when loading libmraa. This commit
adds similar functionality to call mraa_deinit when unloading
libmraa. This is a nice-to-have since it makes identifying other
memory leaks easier.
Signed-off-by: Noel Eck <noel.eck@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>