swift234

Bump the reference count of a function as long as it's sitting
around in the deserializer's .
1,2d
1i
Bump the reference count of a SILFunction as long as it's sitting
around in the deserializer's cache.

If we deserialize a function, then delete it, then deserialize
another reference to it, we'll end up pointing to a deleted
function.  This was causing the bug where IRGen would assert
with "no order number for SIL function definition?"; I can't
seem to find a radar for that, though.

Also, deserialization test cases are hard to write and probably
inherently unstable.

Swift SVN r15908