Fix for syn::Type::Reference. Properly represent a C pointer '*' or r…

[mjhatamy]

…eference '&'

Example of issue:

Rust code:

#[no_mangle]
pub extern "C" fn key_to_hex(raw_hex: &mut [c_char; GXT_KEY_LEN_HEX], raw_key: &[u8; GXT_KEY_LEN])

Incorrect C Code:

void key_to_hex(char (*rawHex)[GXT_KEY_LEN_HEX],
                              const uint8_t (&rawKey)[GXT_KEY_LEN]);

Correct C Code:

key_to_hex(char (&rawHex)[GXT_KEY_LEN_HEX],
                              const uint8_t (&rawKey)[GXT_KEY_LEN]);

Although this is not yet a complete fix but it is a step forward.
Next, is to change a sized C Array without any pointer or reference.