Auto merge of #58741 - varkor:lang-lib-feature-shared-name, r=alexreg
Auto merge of #58741 - varkor:lang-lib-feature-shared-name, r=alexreg

Allow lang and lib features to share names

Fixes https://github.com/rust-lang/rust/issues/58715.

I didn't add a test, because there's currently no standard lang test feature and I felt apprehensive about adding a permanently unstable feature. Instead, a shared lang/lib feature will be used in https://github.com/rust-lang/rust/pull/57760 and will essentially provide an immediately test.

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