Don't inherit the host configuration's fragments from the target config in --experimental_dynamic_configs=notrim mode.

--
MOS_MIGRATED_REVID=135126724
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
index 2037dbb..2d3119c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.ImmutableBiMap;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.analysis.buildinfo.BuildInfoFactory;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
@@ -63,6 +64,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.TreeMap;
 
 import javax.annotation.Nullable;
@@ -716,4 +718,17 @@
   public String getDefaultWorkspaceSuffix() {
     return defaultWorkspaceFileSuffix;
   }
+
+  /**
+   * Returns all registered {@link BuildConfiguration.Fragment} classes.
+   */
+  public Set<Class<? extends BuildConfiguration.Fragment>> getAllFragments() {
+    ImmutableSet.Builder<Class<? extends BuildConfiguration.Fragment>> fragmentsBuilder =
+        ImmutableSet.builder();
+    for (ConfigurationFragmentFactory factory : getConfigurationFragments()) {
+      fragmentsBuilder.add(factory.creates());
+    }
+    fragmentsBuilder.add(getUniversalFragment());
+    return fragmentsBuilder.build();
+  }
 }