Ruby 1.9.1 handle cross compilation better, espescially extensions
(I'm working on ARM at91sam9263-ek).
This patch also disable ruby doc generation and ipv6.
[Peter: fixed ipv6 handling]
Signed-off-by: laurent laffont <laurent.laffont@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>