obsolete, thanks to zulu-jdk directory layout;

--- a/src/Pure/Admin/build_jdk.scala	Wed Jan 06 14:03:49 2021 +0100
+++ b/src/Pure/Admin/build_jdk.scala	Wed Jan 06 14:23:57 2021 +0100
@@ -111,8 +111,6 @@
 
   /* extract archive */
 
-  private def suppress_name(name: String): Boolean = name.startsWith("._")
-
   def extract_archive(dir: Path, archive: Path): JDK_Platform =
   {
     try {
@@ -127,7 +125,7 @@
       }
 
       val dir_entry =
-        File.read_dir(tmp_dir).filterNot(suppress_name) match {
+        File.read_dir(tmp_dir) match {
           case List(s) => s
           case _ => error("Archive contains multiple directories")
         }
@@ -202,9 +200,6 @@
           Files.setPosixFilePermissions(path, perms)
         }
 
-        File.find_files((component_dir + Path.explode("x86_64-darwin")).file,
-          file => suppress_name(file.getName)).foreach(_.delete)
-
         progress.echo("Sharing ...")
         val main_dir :: other_dirs =
           platforms.map(platform => (component_dir + platform.platform_path).file.toPath)