Incorrect float→int conversion

[dhardy]

rand/rand_distr/src/utils.rs

Lines 141 to 147 in bf8b5a9

	fn to_u64(self) -> Option<u64> {
	if self >= 0. && self <= ::core::u64::MAX as f64 {
	Some(self as u64)
	} else {
	None
	}
	}

This function is wrong; to copy my comment from #958:

This is incorrect for 32-bit platforms. Check this out.

This isn't your fault; to_u64 for f64 makes the same mistake. Hmm, even the TryFrom in Rust 1.34 doesn't handle this conversion. I'm starting to hate this topic; seems simple but isn't.

[dhardy]

The offending code was removed in #987 (including uses of it, so there is no replacement).