Do not create InterfaceMethodRewriter for API>=24 when not library desugaring

Change-Id: I4beba8de1877496af49e433d94ebe8f7eff87672
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/LibraryDesugaringOptions.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/LibraryDesugaringOptions.java
index 1a965ae..8c29cba 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/LibraryDesugaringOptions.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/LibraryDesugaringOptions.java
@@ -79,11 +79,11 @@
   }
 
   public boolean isCfToCfLibraryDesugaringEnabled() {
-    return !isLirToLirLibraryDesugaringEnabled();
+    return isEnabled() && !isLirToLirLibraryDesugaringEnabled();
   }
 
   public boolean isLirToLirLibraryDesugaringEnabled() {
-    return options.partialSubCompilationConfiguration != null;
+    return isEnabled() && options.partialSubCompilationConfiguration != null;
   }
 
   public void resetDesugaredLibrarySpecificationForTesting() {