Require bison 3.2 and remove deprecated position.hh includes

[georgthegreat]

As of bison 3.2 (released in 2018)

*** C++: stack.hh and position.hh are deprecated

  When asked to generate a header file (%defines), the lalr1.cc skeleton
  generates a stack.hh file.  This file had no interest for users; it is now
  made useless: its content is included in the parser definition.  It is
  still generated for backward compatibility.

This PR updates the code and handles this deprecation.

[linux-foundation-easycla]

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