Introduce a new token kind 'cxx_defaultarg_end' to mark the end of C++ default...

Introduce a new token kind 'cxx_defaultarg_end' to mark the end of C++ default arguments that were part of
lexed method declarations.

This avoid interference with tokens coming after the point where the default arg tokens were 'injected', e.g. for

typedef struct Inst {
  void m(int x=0);
} *InstPtr;

when parsing '0' the next token would be '*' and things would be messed up.

llvm-svn: 110436