g-calend.adb (Has_53_Weeks): Rename to Last_Year_Has_53_Weeks.

g-calend.adb (Has_53_Weeks): Rename to Last_Year_Has_53_Weeks.

2007-09-26  Hristian Kirtchev  <kirtchev@adacore.com>

	* g-calend.adb (Has_53_Weeks): Rename to Last_Year_Has_53_Weeks. Add a
	call to Jan_1_Day _Of_Week to optimize its performance.
	(Is_Leap): Move the routine to the scope of Week_In_Year.
	(Jan_1_Day_Of_Week): New routine in Week_In_Year which calculates the
	weekday on which January 1 falls of Year - 1 and Year + 1. This function
	avoids calling Time_Of and Split, thus making it more efficent.
	(Week_In_Year): Reimplemented in oder to follow ISO 8601.

	* g-calend.ads (Week_In_Year): Change comment to reflect new
	implementation.

From-SVN: r128790