-Add a define for COGL_HAS_GLIB_SUPPORT, the Visual C++ projects will build
GLib support for COGL for all builds at this time, unless there is a
significant call for the need of a COGL Visual C++ build with no
dependency on GLib
-Pre-define COGL_SYSDEF_POLL* as listed in the default values in commit
74974752 since Windows does not have poll.h and thus does not have special
values for these.
https://bugzilla.gnome.org/show_bug.cgi?id=669785
Reviewed-by: Neil Roberts <neil@linux.intel.com>