topotests: create exabgp cli fifo

topotests: create exabgp cli fifo

Create reate exabgp cli fifo even it is not used in topotests to avoid
this error message:

> 16:21:42 | 2290205 | cli             | could not find the named pipes (exabgp.in and exabgp.out) required for the cli
> 16:21:42 | 2290205 | cli             | we scanned the following folders (the number is your PID):
> 16:21:42 | 2290205 | cli control     |  - /run/exabgp/
> 16:21:42 | 2290205 | cli control     |  - /run/0/
> 16:21:42 | 2290205 | cli control     |  - /run/
> 16:21:42 | 2290205 | cli control     |  - /var/run/exabgp/
> 16:21:42 | 2290205 | cli control     |  - /var/run/0/
> 16:21:42 | 2290205 | cli control     |  - /var/run/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/run/exabgp/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/run/0/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/run/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/var/run/exabgp/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/var/run/0/
> 16:21:42 | 2290205 | cli control     |  - /usr/local/var/run/
> 16:21:42 | 2290205 | cli control     | please make them in one of the folder with the following commands:
> 16:21:42 | 2290205 | cli control     | > mkfifo //run/exabgp.{in,out}
> 16:21:42 | 2290205 | cli control     | > chmod 600 //run/exabgp.{in,out}

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>