swift234

TypeChecker: Remove getStdlibModule() hack that searched all loaded modules.

Instead, just provide a DeclContext. Assume we're compiling the standard
library if there's no module named "swift", and use the parent module of
the current DeclContext. We still cache the result, but since the standard
library can't import any other Swift modules by definition, we know the
only interesting module is this one.

Swift SVN r9945