disable CI rustc when not using CI LLVM

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

src/ci/run.sh

@@ -169,6 +169,8 @@ else
 if [ "$NO_DOWNLOAD_CI_LLVM"="" ];then
  RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.download-ci-llvm=if-unchanged"
 else
+# CI rustc requires CI LLVM to be enabled (see https://github.com/rust-lang/rust/issues/123586).
+ NO_DOWNLOAD_CI_RUSTC=1
 # When building for CI we want to use the static C++ Standard library
 # included with LLVM, since a dynamic libstdcpp may not be available.
  RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.static-libstdcpp"