decl2.c (reparse_absdcl_as_casts): Don't warn about old-style casts in system headers or extern "C" blocks.

	* decl2.c (reparse_absdcl_as_casts): Don't warn about old-style
	casts in system headers or extern "C" blocks.
	* decl2.c (write_virtuals): Deleted declaration.
	* cp-tree.h (write_virtuals): Deleted extern declaration.
	* class.c (finish_struct_1): Removed #if 0'd code that mentions
	write_virtuals.
	* semantics.c (begin_class_definition): Rewrite code to not depend
	on write_virtuals.
	* lex.c (cp_pragma_interface): New function.
	(cp_pragma_implementation): Likewise.
	(handle_cp_pragma): Call them.

From-SVN: r28045