Auto merge of #52744 - RalfJung:align_offset, r=Kimundi
Auto merge of #52744 - RalfJung:align_offset, r=Kimundi

make memrchr use align_offset

I hope I did not screw that up...

Cc @oli-obk who authored the original https://github.com/rust-lang/rust/pull/44537

Fixes #50567 (thanks @bjorn3)

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