[Bug target/79671] [7 Regression] mapnik miscompilation on armv7hl since r235622

["bernd.edlinger at hotmail dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79671

--- Comment #43 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
Would something like this also work?

  union function_buffer
  {
    [...]
    mutable char data;

    function_buffer() {}
    function_buffer(const function_buffer &other)
    {
       __builtin_memcpy(this, &other, sizeof(*this));
    }
    function_buffer& operator = (const function_buffer &other)
    {
       __builtin_memcpy(this, &other, sizeof(*this));
       return *this;
    }
  };