[Bf-committers] CMake version bump for blender2.8

[Jörg Müller]

Hi everyone,

a discussion about our cmake version has started after I merged 
audaspace into blender2.8. Audaspace requires cmake 3.0 as opposed to 
blender's main cmake file which so far requires cmake 2.8.

Now since a version bump has been in discussion already a year ago 
according to Campbell, we think this is a good time to actually do it. 
Last time it was postponed because Debian was not ready. So now I had a 
look at the current versions of cmake in the major distributions [1]:

ubuntu (17.04) - 3.7.2
ubuntu LTS (16.04) - 3.5.1
debian (stable) - 3.7.2
opensuse (42.3) - 3.5.2
fedora (F26) - 3.8.2
pclinuxos - 3.7.2
centos (6) - 2.8.12 (3.6.1 in EPEL)
arch - 3.8.2
mageia (6) - 3.7.2
slackware (14.2) - 3.5.2
gentoo - 3.7.2

According to this list, pretty much everyone should be able to get at 
least cmake 3.5 running. Therefore, I bumped the cmake version to 3.5 
which allows us to use newer cmake features now.

Cheers,
Jörg

[1] https://pkgs.org/download/cmake