Editorial corrections

[jaredhoberock]

From Matthias:

In 5.1 [http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/
n4706.html#parallel.execpol.synopsis] there's a line inline constexpr parallel_policy par{ unspecified };, which should be inline constexpr vector_policy vec{ unspecified }; instead, no?

In 5.6 [http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/
n4706.html#parallel.execpol.objects] the policy objects don't have the
inline keyword. Intentional?