swift234

SIL: Include all witnesses in SILDefaultWitnessTable, not just resilient defaults

Previously SILDefaultWitnessTables only included "resilient" default
implementations, which are currently defined as those that appear at the
end of a protocol, after any requirements without defaults.

However, this was too inflexible. Instead, include all entries in the
SILDefaultWitnessTable, with invalid entries standing in for requirements
without defaults.

Previously, the minimum witness table size was a separate parameter, also
appearing in SIL syntax; now it can be calculated by looking at the entries
themselves. The getResilientDefaultEntries() method of SILDefaultWitnessTable
returns the same result as getEntries() did previously.