Update setup.py
Update setup.py

unicode environment variables break build on Windows.
angr/angr,tyb0807/angr,chubbymaggie/angr,f-prettyland/angr,schieb/angr,axt/angr,iamahuman/angr,chubbymaggie/angr,f-prettyland/angr,axt/angr,tyb0807/angr,angr/angr,iamahuman/angr,angr/simuvex,axt/angr,f-prettyland/angr,iamahuman/angr,schieb/angr,tyb0807/angr,chubbymaggie/angr,angr/angr,schieb/angr