[Bug libstdc++/89164] can construct vector with non-copyable-but-trivially-copyable elements

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89164

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
A similar fix is needed for uninitialized_fill and uninitialized_fill_n
otherwise this still compiles:

  std::vector<X> v3{2, X{}};