Rollup merge of #46356 - daboross:patch-2, r=sfackler
Rollup merge of #46356 - daboross:patch-2, r=sfackler

Reject '2' as a binary digit in internals of b: number formatting

The `radix!` macro generates an implementation of the private trait `GenericRadix`, and the code replaced changes Binary's implementation to no longer accept '2' as a valid digit to print.

Granted, this code is literally only ever called from another method in this private trait, and that method has logic to never hand a '2' to the printing function. Even given this, the code's there, I thought it would be best to fix this for clarity of anyone reading it.

GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,aidancully/rust