On Windows, use `TransliterateCodingFailure` for encoding on `stdout`
and `stderr` (unless the current locale encoding is already a Unicode
encoding, in which case do nothing.)
Relaxed error handling requires base >= 4.4; fix build for GHC <= 7.0.4.
Forgot to conditionally omit all the relevant imports in the previous
commit; oops.
Again, fix on GHC 7.0.4, hopefully.
Remove redundant line. (Churn to prod Travis CI.)
Merge pull request #1743 from ianbollinger/windows-encoding

Relax handling of encoding failures on Windows (fixes #846)