proc.c: Add UnboundMethod#bind_call

`umethod.bind_call(obj, ...)` is semantically equivalent to
`umethod.bind(obj).call(...)`.  This idiom is used in some libraries to
call a method that is overridden.  The added method does the same
without allocation of intermediate Method object.  [Feature #15955]

```
class Foo
  def add_1(x)
    x + 1
  end
end
class Bar < Foo
  def add_1(x) # override
    x + 2
  end
end

obj = Bar.new
p obj.add_1(1) #=> 3
p Foo.instance_method(:add_1).bind(obj).call(1) #=> 2
p Foo.instance_method(:add_1).bind_call(obj, 1) #=> 2
```

1 files changed, 9 insertions, 0 deletions

diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index acaf43e46c..1d59ddb594 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -1140,4 +1140,13 @@ class TestMethod < Test::Unit::TestCase
     assert_equal(m, o.:foo)
     assert_nil(o.method(:foo))
   end
+
+  def test_umethod_bind_call
+    foo = Base.instance_method(:foo)
+    assert_equal(:base, foo.bind_call(Base.new))
+    assert_equal(:base, foo.bind_call(Derived.new))
+
+    plus = Integer.instance_method(:+)
+    assert_equal(3, plus.bind_call(1, 2))
+  end
 end