c++: drop in-charge for dtors without vbases

c++: drop in-charge for dtors without vbases

Constructors and destructors use the in-charge parameter to decide whether
they're responsible for recursing into virtual bases.  Historically all
destructors had this parameter in order to also distinguish the deleting
destructor.  But r151673 in GCC 4.5 changed the deleting destructor to just
call the complete destructor and then operator delete, making the in-charge
parameter no longer relevant for destructors in classes without virtual
bases.  Having it causes confusion in constexpr evaluation, which assumes
that clones will have the same parameters as the cloned 'tor.

gcc/cp/ChangeLog:

	* cp-tree.h (base_ctor_identifier): Adjust comment.
	* call.cc (in_charge_arg_for_name): Abort on deleting dtor.
	* decl2.cc (maybe_retrofit_in_chrg): Don't add it for
	destructors without vbases, either.
	* constexpr.cc (cxx_eval_call_expression): Remove workaround.

gcc/testsuite/ChangeLog:

	* g++.dg/debug/dwarf2/array-3.C: No more 'int' for in-chrg parm.
	* g++.dg/debug/dwarf2/array-4.C: Likewise.