fix VFG test cases.
fix VFG test cases.

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