ruby: update to 2.4.0

ruby: update to 2.4.0

Existing version of ruby-native (2.2.5) was crashing on my machine (and others' too),
yet a functional ruby is necessary to upgrade webkit to a version that less vulnerable
to Spectre.

I've performed the update by copying the ruby recipe directory over from the current
pyro tree; if you want to see the list of specific commits, issue this command:

git log 99656fecf4fa6e24ba49ecb7f26f893e733818a0 meta/recipes-devtools/ruby
(up to commit e593d3aeb2ea5f08d6e0753133fe89e345b339e8)

Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 4734a4b41898e3df252b6234ed1270a915fd1f68)
Signed-off-by: Armin Kuster <akuster808@gmail.com>