Suppress warning: 'iseqval' may be used uninitialized in this function

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37137 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

iseq.c

@@ -581,7 +581,7 @@ rb_iseq_compile_with_option(VALUE src, VALUE file, VALUE absolute_path, VALUE li
     int state;
     rb_thread_t *th = GET_THREAD();
     rb_block_t *prev_base_block = th->base_block;
-    VALUE iseqval;
+    VALUE iseqval = Qundef;
 
     th->base_block = base_block;