swift234

Eliminate ExtensionDecl::(get|set|)Conformances.

Stop storing a conformances array on ExtensionDecls. Instead, always use the conformance lookup table to retrieve conformances (which is lazy and supports multi-file, among other benefits).

As part of this, space-optimize ExtensionDecl's handling of conformance loaders. When one registers a conformance loader, it goes into a DenseMap on ASTContext and gets erased once we've loaded that data, so we get two words worth of space back in each ExtensionDecl.

Swift SVN r26353