build: Fix missing backslashes in lists

https://bugzilla.gnome.org/show_bug.cgi?id=725496
girwriter: Don't add target for delegates without target

Fixes bug 725073.
girwriter: Set scope=call for delegates when async or notified does not apply

Fixes bug 725012.
girparser: Add array_null_terminated, fixes hand-written change in gio
posix: Declare Group.gr_mem as null-terminated

Fixes bug 725149.
glib-2.0: Add missing C header for symlink

Fixes bug 725151.