internal/rosa/llvm: migrate compiler-rt

The newLLVM family of functions predate the package system. This change migrates compiler-rt without changing any resulting artifacts.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/stage0.go

@@ -7,10 +7,10 @@ import (
 )
 
 func (t Toolchain) newStage0() (pkg.Artifact, string) {
-	musl, compilerRT, runtimes, clang := t.NewLLVM()
+	musl, runtimes, clang := t.NewLLVM()
 	return t.New("rosa-stage0", 0, []pkg.Artifact{
 		musl,
-		compilerRT,
+		t.Load(LLVMCompilerRT),
 		runtimes,
 		clang,