CFGBase: fix a potential dereference on None values in _analyze_function_features().
CFGBase: fix a potential dereference on None values in _analyze_function_features().

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