backward.h: removed stale declarations

* include/ruby/backward.h (rb_complex_set_real, rb_complex_set_imag):
  removed useless declarations which have been deprecated from the
  beginning.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64642 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

include/ruby/backward.h

@@ -12,10 +12,6 @@ struct RClass {
 #define DECLARE_DEPRECATED_FEATURE(ver, func) \
     NORETURN(ERRORFUNC(("deprecated since "#ver), DEPRECATED(void func(void))))
 
-/* complex.c */
-DECLARE_DEPRECATED_FEATURE(2.2, rb_complex_set_real);
-DECLARE_DEPRECATED_FEATURE(2.2, rb_complex_set_imag);
-
 /* eval.c */
 DECLARE_DEPRECATED_FEATURE(2.2, rb_disable_super);
 DECLARE_DEPRECATED_FEATURE(2.2, rb_enable_super);