compile.c: constify

* compile.c (method_for_self): constify an argument of build
  function for VC6.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57173 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

compile.c

@@ -7058,7 +7058,7 @@ typedef struct {
 
 static const rb_iseq_t *
 method_for_self(VALUE name, VALUE arg, rb_insn_func_t func,
-		VALUE (*build)(rb_iseq_t *, LINK_ANCHOR *, VALUE))
+		VALUE (*build)(rb_iseq_t *, LINK_ANCHOR *const, VALUE))
 {
     VALUE path, absolute_path;
     accessor_args acc;