Fix python 2.6 compatibility issue introduced by r184615
- argparse_compat library does not support reading environment variables
- should unblock Linux GCC buildbot from running tests again



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@185567 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed