This patch adds assertions to ensure that the frontend passes to the
backend the right number of extra parameters required for build in place
function calls. No functional change.

2019-09-17  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* exp_ch6.ads (Needs_BIP_Task_Actuals): New subprogram.
	* exp_ch6.adb (Add_Task_Actuals_To_Build_In_Place_Call): Code
	cleanup.
	(Check_Number_Of_Actuals): New subprogram.
	(Make_Build_In_Place_Call_In_Allocator): Adding assertion.
	(Make_Build_In_Place_Call_In_Anonymous_Context): Adding
	assertion.
	(Make_Build_In_Place_Call_In_Assignment): Adding assertion.
	(Make_Build_In_Place_Call_In_Object_Declaration): Code cleanup
	plus assertion addition.
	(Needs_BIP_Task_Actuals): New subprogram.
	* sem_ch6.adb (Create_Extra_Formals): Rely on
	Needs_BIP_Task_Actuals() to check if the master of the tasks to
	be created, and the caller's activation chain formals are
	needed.

From-SVN: r275772