Use llvm_runtimes for compiler-rt

Author: daltenty

src/bootstrap/src/core/build_steps/llvm.rs

@@ -479,7 +479,6 @@ impl Step for Llvm {
 
         if helpers::forcing_clang_based_tests() {
             enabled_llvm_projects.push("clang");
-            enabled_llvm_projects.push("compiler-rt");
         }
 
         if builder.config.llvm_polly {
@@ -502,6 +501,10 @@ impl Step for Llvm {
 
         let mut enabled_llvm_runtimes = Vec::new();
 
+        if helpers::forcing_clang_based_tests() {
+            enabled_llvm_runtimes.push("compiler-rt");
+        }
+
         if builder.config.llvm_offload {
             enabled_llvm_runtimes.push("offload");
             //FIXME(ZuseZ4): LLVM intends to drop the offload dependency on openmp.