Create a method `getOutputDirectoryName` on `BuildConfigurationValue` so that callers don't need to handle the host configuration specially.

PiperOrigin-RevId: 444720039
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java
index 6434b74..64b2e9c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java
@@ -446,14 +446,27 @@
   }
 
   /**
-   * Returns the configuration-dependent string for this configuration. This is also the name of the
-   * configuration's base output directory unless {@link #isHostConfiguration} is {@code true}, in
-   * which case the output directory is named {@code host}.
+   * Returns the configuration-dependent string for this configuration.
+   *
+   * <p>This is also the name of the configuration's base output directory unless {@link
+   * #isHostConfiguration} is {@code true}, in which case the output directory is named {@code
+   * "host"}. See also {@link #getOutputDirectoryName}.
    */
   public String getMnemonic() {
     return outputDirectories.getMnemonic();
   }
 
+  /**
+   * Returns the name of the base output directory under which actions in this configuration write
+   * their outputs.
+   *
+   * <p>This is the same as {@link #getMnemonic} except in the host configuration, in which case it
+   * is {@code "host"}.
+   */
+  public String getOutputDirectoryName() {
+    return outputDirectories.getOutputDirName();
+  }
+
   @VisibleForTesting
   public String getTransitionDirectoryNameFragment() {
     return transitionDirectoryNameFragment;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java b/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
index 696ae0e..5d565a8 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
@@ -341,6 +341,10 @@
     return mnemonic;
   }
 
+  String getOutputDirName() {
+    return outputDirName;
+  }
+
   boolean mergeGenfilesDirectory() {
     return mergeGenfilesDirectory;
   }