Undeclared builtin identifiers in C++

Clang Frontend
#1

Hi all,

  I'm trying to use clang to parse a simple C++ file, using the
tutorials from https://github.com/loarabia/Clang-tutorial as my guide.
With files that use standard library types I get errors about
undeclared builtin identifiers:

#2

With files that use standard library types I get errors about
undeclared builtin identifiers:

I wasn't calling InitializeBuiltins on the Preprocessor BuiltinContext
but on one I constructed to pass in to my ASTContext. Correcting this
fixes the errors.