Function callback_logger_handler 

pub unsafe extern "C" fn callback_logger_handler(
    componentEnvironment: *mut c_void,
    instanceName: *const i8,
    status: u32,
    category: *const i8,
    message: *const i8,
    ...
)

Available on crate feature fmi2 only.

This function is implemented in logger.c Note: This can be re-implemented in pure Rust once the c_variadics feature stabilizes. See: https://doc.rust-lang.org/beta/unstable-book/language-features/c-variadic.html