[clang] cc1: Report an error for multiple actions unless separated by -main-file-name (PR #91140)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> CI seems to have noticed what I feared :) This is going to hit a good amount of our internal tests, there is no way our copy-paste cargo-cult didn't come up with this before.

This one-liner might be useful to auto fix some downstream tests...

```
xargs sed -Ei 's/(-fsyntax-only|-emit-obj|-emit-llvm|-emit-llvm-only) (([^|%]|%s|%t)*)(-analyze|-ast-dump|-emit-llvm|-fsyntax-only|-emit-pch|-E|-S)/\2\4/' < /tmp/0
```

https://github.com/llvm/llvm-project/pull/91140