Auto merge of #46581 - tmccombs:drain_filter_drop, r=sfackler
Auto merge of #46581 - tmccombs:drain_filter_drop, r=sfackler

Add Drop impl for linked_list::DrainFilter

This is part of #43244. See https://github.com/rust-lang/rust/issues/43244#issuecomment-349894355

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