Add support for call_depth being None
Add support for call_depth being None

tyb0807/angr,schieb/angr,schieb/angr,angr/angr,f-prettyland/angr,axt/angr,f-prettyland/angr,angr/angr,chubbymaggie/angr,tyb0807/angr,iamahuman/angr,angr/angr,f-prettyland/angr,haylesr/angr,axt/angr,schieb/angr,iamahuman/angr,iamahuman/angr,chubbymaggie/angr,axt/angr,tyb0807/angr,chubbymaggie/angr,haylesr/angr