Auto merge of rust-lang#117328 - lqd:cranelift-rocket, r=<try>

pass `CODEGEN_BACKENDS` to docker

The backends to build are now defined in the `CODEGEN_BACKENDS` env var. It's correctly set in CI, but wasn't passed to docker, hence cg_clif wasn't actually built in rust-lang#81746.

r? `@Kobzol:` I locally tried `CODEGEN_BACKENDS="cranelift" DEPLOY=1 src/ci/docker/run.sh dist-x86_64-linux` and this change was enough for `ci/run.sh` to read the env var. However, we can also see people doing both `--env DEPLOY` as-is and  `--env BASE_COMMIT="$BASE_COMMIT" \` and I wonder why, do you know?

So I'll try as-is and we'll see.

(Opened as draft for your feedback, and for me to get a try build going and look at the artifacts)

src/ci/docker/run.sh

@@ -288,6 +288,7 @@ docker \
   --env DIST_TRY_BUILD \
   --env PR_CI_JOB \
   --env OBJDIR_ON_HOST="$objdir" \
+  --env CODEGEN_BACKENDS \
   --init \
   --rm \
   rust-ci \