Fix build results for aspect builds.

The current output was pretty much completely incorrect. However since the result output was always hidden for the default value of --show_result, users simply didn't see the incorrect output (instead getting no output at all).

This CL fixes both the --show_result problem and makes the output correct.

RELNOTES: Print correct build result for builds with --aspects flag.
PiperOrigin-RevId: 191456352
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AspectCompletionValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/AspectCompletionValue.java
index 7b33d0b..64066cf 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AspectCompletionValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AspectCompletionValue.java
@@ -37,8 +37,9 @@
         targets, aspectValue -> AspectCompletionKey.create(aspectValue.getKey(), ctx));
   }
 
+  /** The key of an AspectCompletionValue. */
   @AutoValue
-  abstract static class AspectCompletionKey implements SkyKey {
+  public abstract static class AspectCompletionKey implements SkyKey {
     public static AspectCompletionKey create(
         AspectKey aspectKey, TopLevelArtifactContext topLevelArtifactContext) {
       return new AutoValue_AspectCompletionValue_AspectCompletionKey(