fixed the issue of file merging failure if any of the file positions is symbolic although the max position could be decided.
fixed the issue of file merging failure if any of the file positions is symbolic although the max position could be decided.

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