ada: Couple of minor fixes for build-in-place calls in anonymous contexts

ada: Couple of minor fixes for build-in-place calls in anonymous contexts

The current code does not deal with all the anonymous contexts uniformly,
since it potentially creates an activation chain and a master only in the
case of an actual in a call; moreover, the master is created in the scope
of the actual's type, instead of in the context of the call like the chain.

The change also aligns Make_Build_In_Place_Call_In_Anonymous_Context with
sibling routines by calling Make_Build_In_Place_Call_In_Object_Declaration
directly instead of letting the expander recursively do it.  It also adds
a missing rewriting in Make_Build_In_Place_Iface_Call_In_Anonymous_Context.

gcc/ada/ChangeLog:

	* exp_ch6.adb (Expand_Actuals): Do not create activation chain and
	master for build-in-place calls here but...
	(Make_Build_In_Place_Call_In_Allocator): Use Unqual_Conv.
	(Make_Build_In_Place_Call_In_Anonymous_Context): ...here instead.
	Call Make_Build_In_Place_Call_In_Object_Declaration directly.
	(Make_Build_In_Place_Iface_Call_In_Anonymous_Context): ...and here
	instead.  Add missing rewriting of the call.