[PATCH] tests/common.sh: Find ss on the PATH

[Nick Clifton]

Hi Mark,

> On Fedora based systems ss is installed in /usr/sbin.
> On Debian based systems ss is installed in /usr/bin.
> Either system has both /usr/bin and usr/sbin on the default PATH.
> 
> With this the debian-i386 and ubuntu-riscv CI builders are zero fail:
> https://builder.sourceware.org/buildbot/#/builders?tags=annobin

Patch approved and applied.  Thanks!

Cheers
   Nick