glib2: don't call g_thread_init() when is uses glib 2.32.0 or higher
glib2: don't call g_thread_init() when is uses glib 2.32.0 or higher

glib thread system is automatically initialized since glib 2.32.0.

ref: https://developer.gnome.org/glib/2.42/glib-Deprecated-Thread-APIs.html#g-thread-init

kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2