swift234

[ClangImporter] Import typedefs of block types as fully-bridged closures.

Block types can't be used in structs (because they're managed by ARC),
are rarely referred to by pointers, and would pretty much never be
globals. Additionally, their syntax is complicated enough that people
tend to make typedefs for them fairly frequently. We'd like to preserve
that sugar, but we don't really need to preserve the representation
when the most likely use of the block is in a bridged context (e.g. a
method parameter). In the rare case where the representation /is/
important, fall back to re-importing the underlying type.

rdar://problem/22013912

Swift SVN r30738