Factor out PathFragment.create("_repo_mapping") to a constant.

No need to create a new instance each time we call `Runfiles#getRunfilesInputs`.

PiperOrigin-RevId: 671470371
Change-Id: Ia168ab7a15e810f55381094db20301ac5373382a

Author: haxorz

src/main/java/com/google/devtools/build/lib/analysis/Runfiles.java

@@ -94,6 +94,9 @@ public void fingerprint(Fingerprint fp) {
   // It is important to declare this *after* the DUMMY_SYMLINK_EXPANDER to avoid NPEs
   public static final Runfiles EMPTY = new Builder().build();
 
+  private static final PathFragment REPO_MAPPING_PATH_FRAGMENT =
+      PathFragment.create("_repo_mapping");
+
   private static final CommandLineItem.ExceptionlessMapFn<SymlinkEntry> SYMLINK_ENTRY_MAP_FN =
       (symlink, args) -> {
         args.accept(symlink.getPathString());
@@ -375,7 +378,7 @@ public Map<PathFragment, Artifact> getRunfilesInputs(
     }
     builder.add(getRootSymlinksAsMap(checker), checker);
     if (repoMappingManifest != null) {
-      checker.put(builder.manifest, PathFragment.create("_repo_mapping"), repoMappingManifest);
+      checker.put(builder.manifest, REPO_MAPPING_PATH_FRAGMENT, repoMappingManifest);
     }
     return builder.build();
   }