[Ada] Unnesting issues with entry families and accept statements

[Ada] Unnesting issues with entry families and accept statements

2019-10-10  Gary Dismukes  <dismukes@adacore.com>

gcc/ada/

	* sem_util.adb (Enclosing_Subprogram): Handle the case of
	E_Entry_Family, returning the entry family's associated
	Protected_Body_Subprogram (as was already done for E_Entry).
	* exp_ch9.adb (Expand_N_Accept_Statement): Call Reset_Scopes_To
	on the block created for an accept statement to reset the scopes
	of any local entities to the block scope.

From-SVN: r276830