Make resize in std::vector bindings not assume a default constructor.

This change uses the std::vector::resize variant that takes a value
argument and uses it if the vector needs to be extended. The previous
attempt of adding resize used the 1 argument version, which required
that the vector's element type has a default constructor.
Merge pull request #3072 from pwnall/vector_resize_fix

Make resize in std::vector bindings not assume a default constructor.