Stop excluding `stdarch` test crates from `rust-src` In the past, this exclusion saved 30MB of heavy intrinsics data from ending up in `rust-src`. However, this filter has been outdated since https://github.com/rust-lang/stdarch/pull/1894, which moved the data to `library/stdarch/intrinsics_data`. These intrinsics have also shrunk since then, and now sit around 12MB (300KB when compressed). So this specific change only adds a few KBs: | `rust-src` | compressed | unpacked | | ---------- | ---------- | -------- | | before | 8.01 MB | 76.5 MB | | after | 8.06 MB | 76.9 MB | The motivation for this change would be simplifying integration of the `stdarch` test suite into `cg_clif`. For completeness, if we instead fixed the filter to point to the new data location, we'd shrink the dist to: | `rust-src` | compressed | unpacked | | ---------- | ---------- | -------- | | filtered | 7.64 MB | 64.7 MB | cc @bjorn3