Function EVP_PKEY_decapsulate 

pub unsafe extern "C" fn EVP_PKEY_decapsulate(
    ctx: *mut EVP_PKEY_CTX,
    unwrapped: *mut c_uchar,
    unwrappedlen: *mut usize,
    wrapped: *const c_uchar,
    wrappedlen: usize,
) -> c_int