test: linux-gen: ipc do not use pid -1 value
test: linux-gen: ipc do not use pid -1 value

In docker $$ (current pid) is 1 for the first launched bash.
0 value in ipc .ns mixed up with NULL and not accepted.
Also .ns value should not overflow signed int type.

Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>
Reviewed-and-tested-by: Bill Fischofer <52f3c909d51cc5d355a68a403df6906b3c1a8f83@linaro.org>

erachmi/odp,erachmi/odp,mike-holmes-linaro/odp,ravineet-singh/odp,mike-holmes-linaro/odp,dkrot/odp,mike-holmes-linaro/odp,nmorey/odp,nmorey/odp,dkrot/odp,dkrot/odp,erachmi/odp,erachmi/odp,nmorey/odp,mike-holmes-linaro/odp,ravineet-singh/odp,ravineet-singh/odp,ravineet-singh/odp,dkrot/odp,nmorey/odp