Ensure that all Breakpoint.java files are identical for CTS

These files all need to be identical in order for us to use these
tests with CTS. Fix the single difference between them.

Test: for i in `find . -name "Breakpoint.java" -type f`; do
        diff $i test/993-breakpoints/src/art/Breakpoint.java;
      done
Bug: 73252141
Change-Id: I9d6e395dae3ff8f196b0dfc310810db8486068be
diff --git a/test/993-breakpoints/src/art/Breakpoint.java b/test/993-breakpoints/src/art/Breakpoint.java
index 2a370eb..bbb89f7 100644
--- a/test/993-breakpoints/src/art/Breakpoint.java
+++ b/test/993-breakpoints/src/art/Breakpoint.java
@@ -117,7 +117,7 @@
                                                  Thread thr);
   public static native void stopBreakpointWatch(Thread thr);
 
-  public static final class LineNumber {
+  public static final class LineNumber implements Comparable<LineNumber> {
     public final long location;
     public final int line;