show warning for unused block

With verbopse mode (-w), the interpreter shows a warning if
a block is passed to a method which does not use the given block.

Warning on:

* the invoked method is written in C
* the invoked method is not `initialize`
* not invoked with `super`
* the first time on the call-site with the invoked method
  (`obj.foo{}` will be warned once if `foo` is same method)

[Feature #15554]

`Primitive.attr! :use_block` is introduced to declare that primitive
functions (written in C) will use passed block.

For minitest, test needs some tweak, so use
ea9caafc07
for `test-bundled-gems`.

lib/optparse.rb

@@ -461,7 +461,7 @@ class OptionParser
       candidates
     end
 
-    def candidate(key, icase = false, pat = nil)
+    def candidate(key, icase = false, pat = nil, &_)
       Completion.candidate(key, icase, pat, &method(:each))
     end
 
@@ -739,7 +739,7 @@ class OptionParser
       #
       # Raises an exception if argument is not present.
       #
-      def parse(arg, argv)
+      def parse(arg, argv, &_)
         unless arg
           raise MissingArgument if argv.empty?
           arg = argv.shift