Fixed a bug in SimArch.get_ret_irsb(). Added support for get_nop_irsb() in SimArch.
Fixed a bug in SimArch.get_ret_irsb(). Added support for get_nop_irsb() in SimArch.

axt/angr,zhuyue1314/simuvex,angr/angr,f-prettyland/angr,chubbymaggie/angr,angr/simuvex,angr/angr,f-prettyland/angr,axt/angr,tyb0807/angr,f-prettyland/angr,tyb0807/angr,chubbymaggie/simuvex,iamahuman/angr,angr/angr,tyb0807/angr,chubbymaggie/simuvex,axt/angr,schieb/angr,chubbymaggie/simuvex,iamahuman/angr,schieb/angr,schieb/angr,iamahuman/angr,chubbymaggie/angr,chubbymaggie/angr