Fixes PR java/9685, PR java/15073
* parse.y (accessibility_string): New method.
(not_accessible_field_error): Use accessibility_string()
instead of java_accstring_lookup().
(resolve_qualified_expression_name): Check with
check_pkg_class_access() before allowing access using
qualified names.
Fix comment typo.
Use check_pkg_class_access() instead of not_accessible_p()
for unqualified types.
(not_accessible_p): Use DECL_CONTEXT (member) instead of
REFERENCE for package-private access checking.
(patch_method_invocation): Use accessibility_string() instead
of java_accstring_lookup().