Initialize the the kb to store results for openvas-nasl.

[jjnicola]

What:
Initialize the the kb to store results for openvas-nasl.

Why:
If not initialized, openvas-nasl can not store results

How:
run a script with openvas-nasl

openvas-nasl -X -B -d -i /home/juan/install/var/lib/openvas/plugins -t www.google.com find_service.nasl --kb="Ports/tcp/443=1"

without the patch you should see an assertion error:

$ openvas-nasl -X -B -d -i /home/juan/install/var/lib/openvas/plugins -t www.google.com find_service.nasl --kb="Ports/tcp/443=1"
lib  misc-Message: 02:41:50.701: replace key FindService/CnxTime1000/443 -> 95
lib  misc-Message: 02:41:50.701: set key Transports/TCP/443 -> 9
openvas-nasl: /home/juan/install/include/gvm/util/kb.h:395: kb_item_push_str: Assertion `kb' failed.

Checklist:

• Tests
• CHANGELOG Entry