qapi stats: Elide redundant has_FOO in generated C

The has_FOO for pointer-valued FOO are redundant, except for arrays.
They are also a nuisance to work with.  Recent commit "qapi: Start to
elide redundant has_FOO in generated C" provided the means to elide
them step by step.  This is the step for qapi/stats.json.

Said commit explains the transformation in more detail.  The invariant
violations mentioned there do not occur here.

Cc: Mark Kanda <mark.kanda@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Mark Kanda <mark.kanda@oracle.com>
Message-Id: <20221018062849.3420573-23-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

monitor/qmp-cmds.c

@@ -560,10 +560,7 @@ void add_stats_entry(StatsResultList **stats_results, StatsProvider provider,
     StatsResult *entry = g_new0(StatsResult, 1);
 
     entry->provider = provider;
-    if (qom_path) {
-        entry->has_qom_path = true;
-        entry->qom_path = g_strdup(qom_path);
-    }
+    entry->qom_path = g_strdup(qom_path);
     entry->stats = stats_list;
 
     QAPI_LIST_PREPEND(*stats_results, entry);

scripts/qapi/schema.py

@@ -759,7 +759,6 @@ def need_has(self):
         assert self.type
         # Temporary hack to support dropping the has_FOO in reviewable chunks
         opt_out = [
-            'qapi/stats.json',
             'qapi/tpm.json',
             'qapi/transaction.json',
             'qapi/ui.json',