exp_util.adb: Minor code reorganization (use N_Short_Circuit)

exp_util.adb: Minor code reorganization (use N_Short_Circuit)

2009-07-10  Robert Dewar  <dewar@adacore.com>

	* exp_util.adb: Minor code reorganization (use N_Short_Circuit)

	* exp_ch4.adb: Add ??? comment for conditional expressions on limited
	types.

	* checks.adb (In_Declarative_Region_Of_Subprogram_Body): New procedure,
	replaces Safe_To_Capture_In_Parameter_Value, and properly handles the
	case of conditional expressions that may not be elaborated.

	* sem_util.adb (Safe_To_Capture_Value): Properly handle case of
	conditional expression where we may not execute then then or else
	branches.

From-SVN: r149468