Introduce basic ASTs for lambda expressions. This covers:
  - Capturing variables by-reference and by-copy within a lambda
  - The representation of lambda captures
  - The creation of the non-static data members in the lambda class
  that store the captured variables
  - The initialization of the non-static data members from the
  captured variables
  - Pretty-printing lambda expressions

There are a number of FIXMEs, both explicit and implied, including:
  - Creating a field for a capture of 'this'
  - Improved diagnostics for initialization failures when capturing
  variables by copy
  - Dealing with temporaries created during said initialization
  - Template instantiation
  - AST (de-)serialization
  - Binding and returning the lambda expression; turning it into a
  proper temporary
  - Lots and lots of semantic constraints
  - Parameter pack captures


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149977 91177308-0d34-0410-b5e6-96231b3b80d8
24 files changed