Allow the use of Python 3 when building GHC
According to the wiki, it is preferred that a user have Python 2.7 installed before attempting to build GHC. As I'm on Arch Linux the default Python version is 3.4. As such, rather than simply changing the shebang line to explicitly ask for version 2, I made it so that the scripts all use syntax that works properly for versions 2.7 to 3.4. I don't think I've used anything that disallows 2.6, but don't have that version available to check against.
I should note that the changes were as minimal as possible. That is, I didn't bother refactoring to use more modern idioms (such as string substitution vs concatenation). As these are helper scripts, I doubt doing so would be much help, but I wouldn't mind doing so upon request.