Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
Note that we can't actually display the latter in textual format (because
the fix-it contains a newline), nor can we verify it (because the fixit
contains a newline).
Swift SVN r4813
