swift234

[SILParser] reconstruct requirements in the same way as how type checker
generates them.

Modify getAsCanonicalGenericSignature to dump same-type requirements last.
Also mix the conformance requirements on assocaited archetypes with the witness
markers.

SILParser used to put witness markers for all assocaited archetypes, then
add same-type requirements, and finally the conformance requirements on
associated archetypes. This causes mismatch types between deserialized
SILFunctionTypes and parsed SILFunctionTypes.

rdar://17998988


Swift SVN r21423