util: do not unref event thread after joining it

g_thread_join() eats a reference.

==295055== Invalid read of size 4
==295055==    at 0x4DA4AE4: g_thread_unref (in /usr/lib64/libglib-2.0.so.0.6400.5)
==295055==    by 0x491D5FA: vir_event_thread_finalize (vireventthread.c:47)
==295055==    by 0x4E6BCFF: g_object_unref (in /usr/lib64/libgobject-2.0.so.0.6400.5)
==295055==    by 0x22F35CF4: qemuProcessQMPFree (qemu_process.c:8525)
==295055==    by 0x22E71B58: glib_autoptr_clear_qemuProcessQMP (qemu_process.h:237)
...
==295055==    by 0x22E98A29: qemuDomainPostParseDataAlloc (qemu_domain.c:5476)
==295055==    by 0x49ABF83: virDomainDefPostParse (domain_conf.c:6023)
==295055==  Address 0x2acb1c68 is 24 bytes inside a block of size 88 free'd
==295055==    at 0x483B9F5: free (vg_replace_malloc.c:538)
==295055==    by 0x4D80A4C: g_free (in /usr/lib64/libglib-2.0.so.0.6400.5)
...
==295055==    by 0x491D5F1: vir_event_thread_finalize (vireventthread.c:46)
==295055==    by 0x4E6BCFF: g_object_unref (in /usr/lib64/libgobject-2.0.so.0.6400.5)
==295055==    by 0x22F35CF4: qemuProcessQMPFree (qemu_process.c:8525)
==295055==    by 0x22E71B58: glib_autoptr_clear_qemuProcessQMP (qemu_process.h:237)
...
==295055==  Block was alloc'd at
==295055==    at 0x483A809: malloc (vg_replace_malloc.c:307)
==295055==    by 0x4D80958: g_malloc (in /usr/lib64/libglib-2.0.so.0.6400.5)
...
==295055==    by 0x4DA4C32: g_thread_try_new (in /usr/lib64/libglib-2.0.so.0.6400.5)
==295055==    by 0x491D3BC: virEventThreadStart (vireventthread.c:159)
==295055==    by 0x491D3BC: virEventThreadNew (vireventthread.c:185)
...

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Fixes: f4fc3db920
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/util/vireventthread.c

@@ -44,7 +44,6 @@ vir_event_thread_finalize(GObject *object)
     if (evt->thread) {
         g_main_loop_quit(evt->loop);
         g_thread_join(evt->thread);
-        g_thread_unref(evt->thread);
     }
 
     g_main_loop_unref(evt->loop);