When RUBY_TEST_TIMEOUT_SCALE is set, the timeout increases by the multiple
specified. However, the test in test4test_hungup.rb does not scale, so
if RUBY_TEST_TIMEOUT_SCALE is a large number like 10, then the test will
not time out causing the tests test to fail.

Single `Integer` argument means an exact match to the major version.

We can handle uri, time and others without `make test-all` dependencies now.

Not only defined in `Test::Unit` or `CoreAssertions`, also show the
caller location of assertion methods defined in the current class or
ancestors.

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
https://github.com/minitest/minitest/commit/ea9caafc0754b1d6236a490d59e624b53209734a
for `test-bundled-gems`.