Function secp256k1_ecdsa_sign
pub unsafe extern "C" fn secp256k1_ecdsa_sign(
cx: *const Context,
sig: *mut Signature,
msg32: *const u8,
sk: *const u8,
noncefn: Option<unsafe extern "C" fn(_: *mut u8, _: *const u8, _: *const u8, _: *const u8, _: *mut c_void, _: u32) -> i32>,
noncedata: *const c_void,
) -> i32