[Ada] Crash in tagged type constructor with task components

[Ada] Crash in tagged type constructor with task components

2020-06-18  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* exp_ch6.adb (BIP_Suffix_Kind, Is_Build_In_Place_Entity): Move
	declarations...
	* exp_ch6.ads: Here.
	* exp_util.adb (Is_Secondary_Stack_BIP_Func_Call): Do not rely
	on the name of the scope to locate the extra formal BIPalloc
	since they are copied when the pointer type associated with
	dispatching calls is built; rely on routines
	Is_Build_In_Place_Entity and BIP_Suffix_Kind.
	* exp_disp.adb (Expand_Dispatching_Call): Set the scope of the
	first extra formal of the internally built pointer type.
	* sem_ch3.adb (Derive_Subprogram): Do not inherit extra formals
	from a limited interface parent since limitedness is not
	inherited in such case (AI-419) and this affects the extra
	formals.
	* sprint.adb (Write_Itype): Output extra formals of subprogram
	types.