spec: Enable glib integration instead of g-main-loop.

--with-glib=always enables glib integration with ecore main loop. Thus
one can use glib APIs with ecore main loop.
--enable-g-main-loop uses g main loop as EFL's main loop instead of
ecore main loop. This option is not recommended and not tested well.

Change-Id: Ia9ea3fef435d026502374017134d45d9893e3ec4
Signed-off-by: Daniel Juyung Seo <juyung.seo@samsung.com>