exp_ch6.ads (BIP_Storage_Pool): New "extra implicit parameter" that gets passed in the same cases where...

2011-10-13  Bob Duff  <duff@adacore.com>

	* exp_ch6.ads (BIP_Storage_Pool): New "extra implicit parameter"
	that gets passed in the same cases where BIP_Alloc_Form is passed
	(caller-unknown-size results). BIP_Storage_Pool is used when
	BIP_Alloc_Form = User_Storage_Pool.  In that case, a pointer
	to the user-defined storage pool is passed at the call site,
	and this pool is used in callee to allocate the result.
	* exp_ch6.adb (Add_Unconstrained_Actuals_To_Build_In_Place_Call): New
	version of Add_Alloc_Form_Actual_To_Build_In_Place_Call. Passes
	the additional BIP_Storage_Pool actual.
	(Expand_N_Extended_Return_Statement): Allocate the function
	result using the user-defined storage pool, if BIP_Alloc_Form =
	User_Storage_Pool.
	* sem_ch6.adb: Add the "extra formal" for BIP_Storage_Pool.
	* exp_ch4.adb: Don't overwrite storage pool set by
	Expand_N_Extended_Return_Statement.
	* s-stopoo.ads, rtsfind.ads (Root_Storage_Pool_Ptr): New type,
	for use in build-in-place function calls within allocators
	where the access type has a user-defined storage pool.

From-SVN: r179903