Auto merge of #42041 - Keruspe:master, r=alexcrichton
Auto merge of #42041 - Keruspe:master, r=alexcrichton

rustbuild: fix bash completion installation dir

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