tests: Make ipc test more portable (#466)

fix a couple of errors reported by covscan

1. /usr/lib64/libqb/tests/resources.test:8:34: warning[SC2039]: In POSIX sh, UID is undefined.
2. /usr/lib64/libqb/tests/resources.test:8:30: warning[SC2166]: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.
3. /usr/lib64/libqb/tests/ipc_sock.test:10:34: warning[SC2039]: In POSIX sh, UID is undefined.
4. /usr/lib64/libqb/tests/ipc_sock.test:10:30: warning[SC2166]: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.