[fs.op.create.symlink]
31 Input/output library [input.output]
31.12 File systems [filesystems]
31.12.13 Filesystem operation functions [fs.op.funcs]
31.12.13.11 Create symlink [fs.op.create.symlink]
void filesystem::create_symlink(const path& to, const path& new_symlink);
void filesystem::create_symlink(const path& to, const path& new_symlink,
error_code& ec) noexcept;
Postconditions: new_symlink resolves to a symbolic link file that contains an unspecified representation of to.