In particular, this is problematic when libraries are loaded dynamically, and
may have newer deployment targets than the main executable.
Swift SVN r26786
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
Refuse to load a module if it was compiled for a different architecture or
OS, or if its minimum deployment target is newer than the current target.
Additionally, provide the target triple as part of pre-loading validation
for clients who care (like LLDB).
Part of rdar://problem/17670778
Swift SVN r24469
