Function inject_preloads 

pub fn inject_preloads(
    envv: Vec<CString>,
    injected_preloads: &[PathBuf],
) -> Vec<CString>

Inject injected_preloads into the environment envv.

• Ordering of envv is preserved.
• Ordering of preloads already in envv is preserved.
• Addition of duplicate entries from injected_preloads is suppressed (to avoid unbounded growth of env through chain of execve’s)