Get newest config.guess script.

[fabianbl]

Current config.guess script form glog-0.3.5 is not able to guess the system name for an aarch64 architecture (e.g. Jetson TX2).

[mfehr]

lgtm, one comment though, will glog_catkin fail if the download of the config file fails? If it is, then you might want to consider adding a retry or sth for people with less stable internet connections (an issue that appears now quite often for some maplab users).

[fabianbl]

@mfehr haha good point, I will add something. thanks for reviewing!

update:
wget retries to download the files 20 times by default (and actually glog_catkin also need to be downloaded, otherwise cmake will already fail there)

[meyerj]

Actually #24 would also have fixed this. The repo should not contain those files which are generated by autotools. See also google/glog#188.