ci: link lib[au]san with init.lxc.static statically
init.lxc.static is run in arbitrary containers where the libasan library lxc has been built with
isn't always installed. To make it work let's override GCC's default and link both libasan
and libubsan statically. It should help to fix issues like
```
++ lxc-execute -n c1 -- sudo -u ubuntu /nnptest
lxc-init: error while loading shared libraries: libasan.so.5: cannot open shared object file: No such file or directory
```