do not call g_thread_init() for glib >= 2.31

glib >= 2.31 always enables thread support and g_thread_supported()
is #defined to 1, there's no need to call g_thread_init() anymore,
and it definitely does not need to report error which never happens.
Keep code for old < 2.31 glibc anyway for now, just #ifdef it
differently.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-trivial@nongnu.org

coroutine-gthread.c

@@ -115,14 +115,11 @@ static inline GThread *create_thread(GThreadFunc func, gpointer data)
 
 static void __attribute__((constructor)) coroutine_init(void)
 {
-    if (!g_thread_supported()) {
 #if !GLIB_CHECK_VERSION(2, 31, 0)
+    if (!g_thread_supported()) {
         g_thread_init(NULL);
-#else
-        fprintf(stderr, "glib threading failed to initialize.\n");
-        exit(1);
-#endif
     }
+#endif
 
     init_coroutine_cond();
 }

util/osdep.c

@@ -436,23 +436,20 @@ int socket_init(void)
     return 0;
 }
 
-/* Ensure that glib is running in multi-threaded mode */
+#if !GLIB_CHECK_VERSION(2, 31, 0)
+/* Ensure that glib is running in multi-threaded mode
+ * Old versions of glib require explicit initialization.  Failure to do
+ * this results in the single-threaded code paths being taken inside
+ * glib.  For example, the g_slice allocator will not be thread-safe
+ * and cause crashes.
+ */
 static void __attribute__((constructor)) thread_init(void)
 {
     if (!g_thread_supported()) {
-#if !GLIB_CHECK_VERSION(2, 31, 0)
-        /* Old versions of glib require explicit initialization.  Failure to do
-         * this results in the single-threaded code paths being taken inside
-         * glib.  For example, the g_slice allocator will not be thread-safe
-         * and cause crashes.
-         */
-        g_thread_init(NULL);
-#else
-        fprintf(stderr, "glib threading failed to initialize.\n");
-        exit(1);
-#endif
+       g_thread_init(NULL);
     }
 }
+#endif
 
 #ifndef CONFIG_IOVEC
 /* helper function for iov_send_recv() */