qtest: don't use system command to avoid double fork

Currently we waitpid on the child process we spawn off that does
nothing more than system() another process.  While this does not
appear to be incorrect, it's wasteful and confusing so get rid of
it.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1366123521-4330-2-git-send-email-aliguori@us.ibm.com