cannot compile jtreg with jdk-19

Origin: upstream, f4f1a41e4a
Bug: https://bugs.openjdk.org/browse/CODETOOLS-7903346
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1057511
Forwarded: not-needed
Applied-Upstream: f4f1a41e4add3187b2c73f95c06591ae2de475a4

Java 19 introduced a [serial] linter warning. The build fails due to
'[serial] non-transient instance field of a serializable class declared with
a non-serializable type'.

Gbp-Pq: Name java21-suppress-serial.patch

src/share/classes/com/sun/javatest/diff/SuperDiff.java

@@ -212,10 +212,9 @@ class SuperDiff extends Diff {
         }
     }
 
+    @SuppressWarnings("serial")
     static class SuperTable extends TreeMap<YearDay, Map<String, File>> {
 
-        static final long serialVersionUID = 5933594140534747584L;
-
         SuperTable(File inDir, String resultPath) {
             super();
             for (File pDir : inDir.listFiles()) {