ruby: write operating_system.rb in post_install
ruby: update 2.1.5 bottle.
ruby: fix for --with-suffix
eigen: modernize

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
eigen 3.2.3

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
eigen: install FindEigen3.cmake

Fixes #35225.
Closes #35243.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
eigen: update 3.2.3 bottle.