`Kernel#p` should return an array of arguments; fix #4083

Although the return value is not defined in ISO, it is better to behave
as CRuby does.

mrbgems/mruby-print/mrblib/print.rb

@@ -45,7 +45,7 @@ module Kernel
       __printstr__ "\n"
       i += 1
     end
-    args[0]
+    args.__svalue
   end
 
   unless Kernel.respond_to?(:sprintf)