re PR debug/36278 (ICE with typedef void in namespace and using the defined type in another when compiling with "-g")

	PR debug/36278
	* dwarf2out.c (get_context_die): New function.
	(force_decl_die, force_type_die): Use it.
	(dwarf2out_imported_module_or_decl): Likewise.  If base_type_die
	returns NULL, force generation of DW_TAG_typedef and put that into
	DW_AT_import.

	* g++.dg/debug/namespace2.C: New test.

From-SVN: r138361