Auto merge of #37624 - xen0n:remove-bogus-mipsel-arches, r=alexcrichton
Auto merge of #37624 - xen0n:remove-bogus-mipsel-arches, r=alexcrichton

Remove mention of mipsel target_arch

This is the only remaining instance in rustc. All others were in the libc repo, removed with rust-lang/libc#445.

Actually there's more to clean in `libsyntax/abi.rs`, but let's save that for another commit...

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