gfio: remove warning on g_type_init() being deprecated

Compile throws this on newer glib:

gfio.c: In function ‘init_ui’:
gfio.c:1690:2: warning: ‘g_type_init’ is deprecated (declared at /usr/include/glib-2.0/gobject/gtype.h:667) [-Wdeprecated-declarations]
  g_type_init();
  ^

Fix it with a GLIB_CHECK_VERSION() check for 2.36.0.

Signed-off-by: Jens Axboe <axboe@fb.com>