The mapping of the return value of the `FlsAlloc` was flipped resulting
in the failure of the TLS key creation. The test suite would fail to
generate the TLS key resulting in failures.
Due to the build ordering, I didn't notice this earlier. The inclusion
of the header would define the guard, preventing the needed definitions.
Unconditionally define the functions to ensure that they are available.
Fix syntactic issues in the swift runtime build from the recent TLS changes.
Move the helper definitions into the TLS stubs rather than emitting them
everywhere. This allows the runtime to build again on Windows.
