hamt tests: Fix test failure with Sun C on Solaris 10/SPARC

[Bruno Haible]

Running a testdir on Solaris 10/SPARC with Sun C, I see a test failure:

$ ./test-hamt                                                                   
                                               
$ echo $?                                                                       
                                               
1

No assertion is failing; just the exit code is wrong. This patch fixes it.


2023-04-28  Bruno Haible  <br...@clisp.org>

        hamt tests: Fix test failure with Sun C on Solaris 10/SPARC.
        * tests/test-hamt.c (main): Finish with exit code 0.

diff --git a/tests/test-hamt.c b/tests/test-hamt.c
index 6fdffeac06..ff5df6e19a 100644
--- a/tests/test-hamt.c
+++ b/tests/test-hamt.c
@@ -376,4 +376,6 @@ main (void)
   test_functional_update ();
   test_destructive_update ();
   test_iterator ();
+
+  return 0;
 }