Auto merge of #148992 - Zalathar:rollup-c1aqvox, r=Zalathar

Rollup of 3 pull requests

Successful merges:

 - rust-lang/rust#145954 (stabilize extern_system_varargs)
 - rust-lang/rust#148962 (fix(span): track unnormalized source len for dep-info)
 - rust-lang/rust#148969 (compiletest: Don't apply "emscripten" directives to `wasm32-unknown-unknown`)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors