Rather than go through reentrant and problematic contortions to make Swift
work with the existing Instruments hooks, they agreed to just patch some
globals that we provide to get their logic to be activated.
Swift SVN r17144
Now that we can read definitions directly from "C" headers, stop trying
to maintain a mirror of the HeapObject struct in Swift code in the
standard library.
Swift SVN r14982
Implicit conversions to and from an unsigned long long enum class give us the calling convention we want for swift_allocBox without totally destroying the API for C callers.
Swift SVN r14919
