How to correctly select gcc / why dkms rebuild failed on xtables-addons

[Neo <neo@spacerat.ch>]

Hey folks

I've had a setup with xtables-addons running (on jessie with standard 
repos), especially the geoip module in this case. The normal upgrade 
path installed gcc-4.9 and broke my dkms setup and in turn my iptables 
setup. So it fell back on my fail2ban protection against ssh scripts.

/usr/bin/gcc-4.8 was on strange file permissions, with not even execute 
perms for root. Thus de dkms rebuild failed.

now my questions:

why was gcc-4.8 binary set to no execution, even for root?

why is xtables-addons-dkms not using gcc-4.9?

a simple chmod 700 /usr/bin/gcc-4.8 fixed the problem.

Thank you for any enlightenment

best regards