ibar: add some safeguards to make sure an icon has an exe_current before trying to get list data from it.
ibar: add some safeguards to make sure an icon has an exe_current
before trying to get list data from it.

NB: Safeguards added to stop crashes from happening during a
mouse_wheel (reported from Guy Martin).

Signed-off-by: Chris Michael <177aeddb9e34930a357ecd8dd2d21c80fe280c85@samsung.com>

rvandegrift/e,tasn/enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment,rvandegrift/e,FlorentRevest/Enlightenment,rvandegrift/e,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment