Objective-C, Darwin : Use special string sections for V2 NeXT runtime.

Objective-C, Darwin : Use special string sections for V2 NeXT runtime.

Newer versions of the runtime expect to find strings for class, method
and method types in set-aside sections rather than the general c_strings
one.

gcc/ChangeLog:

	* config/darwin-sections.def (objc2_class_names_section,
	objc2_method_names_section, objc2_method_types_section): New
	* config/darwin.c (output_objc_section_asm_op): Output new
	sections.  (darwin_objc2_section): Select new sections where
	used.

gcc/objc/ChangeLog:

	* objc-next-runtime-abi-02.c
	(next_runtime_abi_02_init_metadata_attributes): Attach metadata
	for the special string sections to class, method and method type
	string sections.