Rollup merge of #34545 - sanxiyn:rustbuild, r=alexcrichton
Rollup merge of #34545 - sanxiyn:rustbuild, r=alexcrichton

Add rustc-stageN targets to rustbuild

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