The `__future__` we relied on is now, where the 3 specific things are
all included [since Python 3.0](https://docs.python.org/3/library/__future__.html):
* absolute_import
* print_function
* unicode_literals
* division
These import statements are no-ops and are no longer necessary.
In order to access `stdin`, `stdout` as binary, you must use the
`buffer` member in Python 3. The replacement of the binary data
requires that pattern and the replacement be byte objects. Convert the
pattern and replacement to UTF-8 encoded bytes.
Rather than use pre-generated swiftmodule files, generate an empty module
and then replace the target triple embedded in it. This unfortunately
necessitates an external script beacuse typical command-line tools are not
meant for operating on binary files.
Swift SVN r24556
