[Ada] CCG: reduce generated temporaries

[Ada] CCG: reduce generated temporaries

2019-07-04  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* exp_aggr.adb (In_Place_Assign_OK): Moved to top level and add
	support for record aggregates.
	(Component_Check): Use Is_CCG_Supported_Aggregate instead of a
	similar local predicate.
	(Convert_To_Assignments): Take advantage of In_Place_Assign_OK
	predicate when possible.
	(Is_CCG_Supported_Aggregate): Return False for records with
	representation clauses and fix the logic for dealing with nested
	aggregates.

From-SVN: r273049