swift234

SIL Serialization: handle more SILInstructions

Use a worklist in SIL linking to traverse the newly serialized SILFunction.
Add serialization/deserialization of the following SILInstructions:
AllocArray, Apply, FunctionRef, IntegerLiteral, Metatype, StructExtract,
Struct and Tuple.

Make getDecl and getIdentifier in ModuleFile public to be used by
SILDeserializer, also make addDeclRef and addIdentifierRef in Serializer
public to be used by SILSerializer.

Update testing case to cover the above SILInstructions.

TODO: lookupSILFunction should replace the existing empty SILFunction instead
of creating a new SILFunction.


Swift SVN r8339