This change is followup for the discussion at ml:
http://lists.opensuse.org/opensuse-factory/2013-08/msg00174.html

I would propose proceed by the schedule I mentioned there.
Most of this stuff is taken from what I did in Gentoo cmake system.

- One more backslash here.

- Backshlashes were missing in macros.

- Add opensuse_rules.cmake to set the default compiler and linker
opts. Tweak a bit the macro to not let upstreams twerk with the
cmake files too much.

- Provide macros.cmake which contains %cmake macro to reduce
mess in the spec files. (forwarded request 195426 from scarabeus_iv)