Record and output access specifiers for nested typedefs

Record and output access specifiers for nested typedefs

We currently do not record access information for typedefs defined inside
classes.  Consider:

struct foo
{
   typedef int PUBLIC;
 private:
   typedef int PRIVATE;
   PRIVATE b;
};

(gdb) ptype foo
type = struct foo {
  private:
    PRIVATE b;

    typedef int PRIVATE;
    typedef int PUBLIC;
}

This patch fixes this:

(gdb) ptype foo
type = struct foo {
  private:
    PRIVATE b;

    typedef int PRIVATE;
  public:
    typedef int PUBLIC;
}

gdb/ChangeLog:

	* c-typeprint.c (enum access_specifier): Moved here from
	c_type_print_base.
	(output_access_specifier): New function.
	(c_type_print_base): Consider typedefs when assessing
	whether access labels are needed.
	Use output_access_specifier as needed.
	Output access specifier for typedefs, if needed.
	* dwarf2read.c (dwarf2_add_typedef): Record DW_AT_accessibility.
	* gdbtypes.h (struct typedef_field) <is_protected, is_private>: New
	fields.
	(TYPE_TYPEDEF_FIELD_PROTECTED, TYPE_TYPEDEF_FIELD_PRIVATE): New
	accessor macros.

gdb/testsuite/ChangeLog:

	* gdb.cp/classes.cc (class_with_typedefs, class_with_public_typedef)
	(class_with_protected_typedef, class_with_private_typedef)
	(struct_with_public_typedef, struct_with_protected_typedef)
	(struct_with_private_typedef): New classes/structs.
	* gdb.cp/classes.exp (test_ptype_class_objects): Add tests for
	typedefs and access specifiers.