integer_arithmetic gives unhelpful warnings for const expressions

[ssokolow]

I use the integer_arithmetic lint as a reminder to explicitly decide on what kind of behaviour I want, but it also triggers in situations like this line, where the math makes the line more readable and the *_mul methods aren't available.

pub const MAX_SCRIPT_SIZE: u64 = 1024 * 1024; // 1 MiB

It should probably be limited to non-constant expressions (or split into two lints) until an alternative is stabilized.

[phansch]

This was fixed as part of #3331 so I'm going to go ahead and close this issue, thank you for the report!