internal/rosa: drop caches

This enables accurate benchmarking of the toolchain abstraction.

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

internal/rosa/rosa_test.go

@@ -91,3 +91,13 @@ func TestCureAll(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkStage3(b *testing.B) {
+	for b.Loop() {
+		rosa.Std.Load(rosa.LLVMClang)
+
+		b.StopTimer()
+		rosa.DropCaches()
+		b.StartTimer()
+	}
+}