swift234

IRGen: Build correct TypeInfos for thin and thick function types.

Derive the appropriate ExtraData for a SILFunctionType from its thinness and calling convention. Consider @!thin @cc(witness_method) as having ExtraData::Metatype. This should eliminate all of the unspoken gentleperson's agreements that let thin and witness functions survive IRGen currently when we can turn on SIL witness tables.

Swift SVN r11446