bind: fix goslice indirection
bind: fix goslice indirection

Change-Id: Icb6ea58ef0f6fc9ecbdb7288f75d627878e3d68e

kellrott/gopy,go-python/gopy,go-python/gopy-gen,ericsnowcurrently/gopython-gopy,ericsnowcurrently/gopython-gopy,go-python/gopy,lifei/gopy,lifei/gopy,kellrott/gopy,go-python/gopy-gen