Remove unused variable.

Author: nirvdrum

lib/truffle/truffle/cext_ruby.rb

@@ -20,7 +20,6 @@ def rb_define_method(mod, name, function, argc)
       raise ArgumentError, "arity out of range: #{argc} for -2..15"
     end
 
-    wrapper = RB_DEFINE_METHOD_WRAPPERS[argc]
     method_body = Truffle::Graal.copy_captured_locals -> *args, &block do
       if argc == -1 # (int argc, VALUE *argv, VALUE obj)
         args = [function, args.size, Truffle::CExt.RARRAY_PTR(args), Primitive.cext_wrap(self)]