* configure.ac: Do not check for g_type_init because we

* configure.ac: Do not check for g_type_init because we
require glib >= 2.28 for GTK3, glib >= 2.10 for GTK2,
glib >= 2.26 for GSettings and glib >= 2.7.0 for GConf, so
suitable glib should provide g_type_init unconditionally.
* src/image.c (fn_g_type_init) [WINDOWSNT]: Define and load
only if Glib < 2.36.0.
(fn_g_type_init) [!WINDOWSNT]: Define only if Glib < 2.36.0.
* src/xsettings.c (init_gconf, init_gsettings): Do not check
for g_type_init.