Add logic for grabbing file descriptor from FILE struct
Add logic for grabbing file descriptor from FILE struct

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