swift234

SIL: Redefine archetype_method in the SIL-witness-tables regime to return an unsubstituted witness.

Clear up the last bit of wanton implicit behavior in archetype_method by having it return the witness as a thin function generic on <Self: P>. Applying the result with <Self = T> will then naturally provide the polymorphic context parameters required by the witness. Tweak the implementation of SILFunctionType::substGenericArgs to handle a substitution for the Self archetype.

Swift SVN r11316