gdb/

gdb/
	Fix modification of cplus_struct_default.
	* dwarf2read.c (dwarf2_add_member_fn) <no DW_AT_vtable_elem_location>:
	Call ALLOCATE_CPLUS_STRUCT_TYPE.
	* gdbtypes.c (cplus_struct_default): New empty initializer, comment it.

gdb/testsuite/
	* gdb.cp/virtbase.cc (class RTTI_base, class RTTI_data)
	(main) <rtti_data>: New.
	* gdb.cp/virtbase.exp (print rtti_data): New.