This is the new and improved version of
__attribute__((annotate("swift1_unavailable"))), with the "improved" being
specifically that the 'availability' attribute supports a message.
This requires a corresponding Clang commit.
Swift side of rdar://problem/18768673.
Swift SVN r27053
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
I can't quite figure out why there is no diagnostic here
for the function being unavailable; this test is failing
the buildbots, and at this point I suspect the test is
wrong rather than the logic. I'll investigate more with
my own iOS build of Swift.
Swift SVN r19226
