swift234

SIL Serialiation: pass in a SILModule to serialize and a few other functions.

Add SerializeSIL.cpp for basic implementation of a SIL serializer.

serialize, serializeToStream, Serializer::writeToStream, and
Serializer::writeTranslationUnit all take an additional SILModule to pass it
to Serializer::writeSILFunctions.

Serializer::writeSILFunctions goes through all SILFunctions in a SILModule, and
serializes all SILFunctions that are transparent.


Swift SVN r7875