Make some skyframe and lib/skyframe classes public.

--
MOS_MIGRATED_REVID=99197069
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/GlobFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/GlobFunction.java
index 942a201..7e80689 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/GlobFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/GlobFunction.java
@@ -39,7 +39,7 @@
  *
  * <p>This code drives the glob matching process.
  */
-final class GlobFunction implements SkyFunction {
+public final class GlobFunction implements SkyFunction {
 
   private final Cache<String, Pattern> regexPatternCache =
       CacheBuilder.newBuilder().concurrencyLevel(4).build();