Don't use STL containers in DLL interface

[AonekoSS]

We can't call it in other implementation or languages.

argument for skip layer guidance
std::vector<int> skip_layers = {},
https://github.com/leejet/stable-diffusion.cpp/blob/master/stable-diffusion.h#L169
https://github.com/leejet/stable-diffusion.cpp/blob/master/stable-diffusion.h#L193

[Green-Sky]

@stduhpf you slipped in c++ into the c header again #451

[stduhpf]

Oops

[stduhpf]

Good catch