Rollup merge of #43203 - jackpot51:patch-2, r=alexcrichton
Rollup merge of #43203 - jackpot51:patch-2, r=alexcrichton

Remove obsolete oom handler from sys::redox

Alloc no longer has set_oom_handler.

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