qemu_monitor_json: Don't leak "option" in qemuMonitorJSONGetCommandLineOptions()

In recent commit of bf8bd93df0 (and friends) we switched the way
we process queried command line arguments: from string lists to
virJSONValue stored in a hash table. To achieve this
qemuMonitorJSONGetCommandLineOptions() helper was introduced
which executes the "query-command-line-options" monitor command
and then calls virJSONValueArrayForeachSteal() to process the
output. The array process function is also given
qemuMonitorJSONGetCommandLineOptionsWorker() as the callback
which is called over each item of the returned array. This
callback then steals "parameters" attribute of each array iteam
storing it in the hash table, but it leaves behind "option"
attribute (because it's g_strdup()-ed). After all of this, the
callback returns 0 which is a signal to the array processing
function that the callback took ownership of the array item. But
this is not true. While it removed "parameters" it did not take
the rest ("option" for instance). And therefore, it leads to a
memory leak:

 5,347 (1,656 direct, 3,691 indirect) bytes in 69 blocks are definitely lost in loss record 2,752 of 2,794
 at 0x483BEC5: calloc (vg_replace_malloc.c:760)
 by 0x4E25A10: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.6400.5)
 by 0x4943317: virJSONValueNewObject (virjson.c:569)
 by 0x4945692: virJSONParserHandleStartMap (virjson.c:1768)
 by 0x5825A86: yajl_do_parse (in /usr/lib64/libyajl.so.2.1.0)
 by 0x4945BFA: virJSONValueFromString (virjson.c:1896)
 by 0xAF5C115: qemuMonitorJSONIOProcessLine (qemu_monitor_json.c:224)
 by 0xAF5C45E: qemuMonitorJSONIOProcess (qemu_monitor_json.c:279)
 by 0xAF4BB6C: qemuMonitorIOProcess (qemu_monitor.c:342)
 by 0xAF4C444: qemuMonitorIO (qemu_monitor.c:574)
 by 0x4FEF846: socket_source_dispatch (in /usr/lib64/libgio-2.0.so.0.6400.5)
 by 0x4E1F727: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.6400.5)

The callback must return 1 so that the array item is properly
freed.

Fixes: ebeff6cd57
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/qemu/qemu_monitor_json.c

@@ -6357,7 +6357,7 @@ qemuMonitorJSONGetCommandLineOptionsWorker(size_t pos G_GNUC_UNUSED,
     g_hash_table_insert(options, g_strdup(name), parameters);
     parameters = NULL;
 
-    return 0;
+    return 1;
 }