Auto merge of rust-lang#125426 - jieyouxu:rmake-support-env-reset, r=saethlin

Update `compiler-builtins` test to not clear essential env vars

Noticed in rust-lang#122580 (comment), the `compiler-builtins` test failed on Windows for a `cargo` invocation because necessary env vars `TMP` and `TEMP` were cleared by `Command::env_clear`, causing temp dir eventually used by codegen to fallback to the Windows directory, which will trigger permission errors.

This PR removes the `env_clear` on the cargo invocation.

r? `@saethlin` (feel free to reroll, since you authored the test)

try-job: x86_64-msvc
try-job: test-various

Author: bors

tests/run-make/compiler-builtins/rmake.rs

@@ -56,7 +56,6 @@ fn main() {
         "--target",
         &target,
     ])
-    .env_clear()
     .env("PATH", path)
     .env("RUSTC", rustc)
     .env("RUSTFLAGS", "-Copt-level=0 -Cdebug-assertions=yes")