Integrated two high-value Clang fixes:

- Clang now completes all Objective-C objects (if
  they are not already complete, and they have
  external lexical sources) during structure
  layout, avoiding a LLDB crash.

- The Clang Decl printer handles reference types
  correctly.  This prevents LLDB from crashing
  when expression logging is enabled.

llvm-svn: 152897