Fixed uname for 32-bit.
Fixed uname for 32-bit.

Stolen from @stef at https://github.com/angr/simuvex/pull/102/files
f-prettyland/angr,f-prettyland/angr,axt/angr,tyb0807/angr,chubbymaggie/angr,angr/angr,schieb/angr,axt/angr,chubbymaggie/angr,angr/angr,tyb0807/angr,iamahuman/angr,tyb0807/angr,chubbymaggie/angr,axt/angr,f-prettyland/angr,iamahuman/angr,angr/angr,iamahuman/angr,schieb/angr,schieb/angr