swift234

Serialization: Fix a couple of issues with serializing context params of generic SILFunctions.

- Parameterize maybeReadGenericParams' BitstreamCursor so that we can read from the correct cursor when trying to read the generic params of a SILFunction.
- Only serialize the context generic params for SILFunctions for which we're serializing a complete definition. This fixes issues with us getting the wrong archetypes forward-declared from references in other modules.

In this version of the patch, we adjust the deserialization point for the generic param list to correctly come before we check if the SILFunction block is empty, and we add a kludge to keep the JIT from crapping itself when it sees the same transparent definition in multiple REPL lines' modules <rdar://problem/16094902>.

Swift SVN r14030