swift234

ClangImporter: Support unnamed struct and union types

This covers this case:

struct foo {
  struct {
    int x;
    int y;
  } bar;

  union {
    void *ptr;
    float num;
  } baz;
};

Based on the original patch by Graham Batty.

Progress on <rdar://problem/21683348> -- anonymous unnamed unions
are still not supported (struct foo { union { int x, y }; };).

Swift SVN r31924