Mark the following functions G_GNUC_CONST (to allow betteroptimization)

Mark the following functions G_GNUC_CONST (to allow betteroptimization)

2000-08-25 Elliot Lee <sopwith@redhat.com>
	* glib.h, gunicode.h, gmodule/gmodule.h:
	Mark the following functions G_GNUC_CONST (to allow
	betteroptimization) because their results are a function of only their parameters:
	g_int_hash, g_int_equal, g_direct_hash, g_direct_equal, g_quark_to_string,
	g_date_is_leap_year, g_date_days_in_month, g_date_monday_weeks_in_year,
	g_date_sunday_weeks_in_year, g_spaced_primes_closest, g_unichar_is*,
	g_unichar_to*, g_unichar_*digit_value, g_unichar_type