[Ada] Fix spurious violations of No_Secondary_Stack restriction

[Ada] Fix spurious violations of No_Secondary_Stack restriction

Now that finalization and return on the secondary stack are decoupled, the
transient scopes created because of the former need not necessarily manage
the secondary stack and trigger a violation of the associated restriction.

gcc/ada/

	* exp_ch7.adb (Wrap_Transient_Declaration): Propagate Uses_Sec_Stack
	to enclosing function if it does not return on the secondary stack.
	* exp_ch6.adb (Expand_Call_Helper): Call Establish_Transient_Scope
	with Manage_Sec_Stack set to True only when necessary.
	* sem_res.adb (Resolve_Call): Likewise.
	(Resolve_Entry_Call): Likewise.