ruby: fix the reproducibility issue

Apply some changes on the Ruby makefiles in order to fix the reproducibility:
- use a fixed timestamp,
- sort linked objects,
- doesn't use the current date,
- and use UTC date.

[YOCTO #14268]

Signed-off-by: Thomas Perrot <thomas.perrot@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>