[Ada] Correctly reject record aggregate using brackets

[Ada] Correctly reject record aggregate using brackets

Ada 2022 bracket syntax is only allowed for arrays and containers, not
records. This change correctly rejects record aggregates using brackets
along with few cases of brackets being used instead of parentheses.

gcc/ada/

	* libgnat/a-direct.adb (Start_Search_Internal): Use parentheses
	for record aggregate.
	* libgnat/a-stbubo.adb (Get_UTF_8): Likewise.
	* libgnat/a-stbuun.adb (Get_UTF_8): Likewise.
	* libgnat/a-stzbou.ads (Null_Bounded_Wide_Wide_String):
	Likewise.
	* libgnat/a-swmwco.ads (Lower_Case_Mapping, Basic_Mapping):
	Likewise.
	* libgnat/a-szmzco.ads (Lower_Case_Mapping, Basic_Mapping):
	Likewise.
	* libgnat/s-statxd.adb (Fields): Likewise.
	* libgnat/s-stausa.adb (Initialize): Likewise.
	* sem_aggr.adb (Resolve_Record_Aggregate): Reject aggregates
	using brackets.