re PR c++/25895 (wrong code with ?: and derived class pointers)

	PR c++/25895
	* class.c (build_base_path): Generate a NOP_EXPR instead of a
	COMPONENT_REF if the base and derived classes are at the same
	address.
	PR c++/25856
	* decl.c (begin_destructor_body): Robustify.
	PR c++/25858 
	* parser.c (cp_parser_direct_declarator): Robustify.
	
	PR c++/25895
	* g++.dg/inherit/conv2.C: New test.
	PR c++/25856
	* g++.dg/parse/dtor7.C: New test.
	PR c++/25858
	* g++.dg/template/crash44.C: New test.

From-SVN: r110084