The change in r206686 to allow the stop argument to work for a service

The change in r206686 to allow the stop argument to work for a service
that is running even though not _enable'd had an annoying side effect.
If the service was already started at boot time by another means when
the related script came around again in rcorder it would start again,
regardless of _enable, because there was a valid pid. [1]

So, split the test into 2 parts, one for (!rcvar && !stop), and one
for (stop && !valid_pid). This preserves the behavior from r206686
while preventing the undesired side effect.

PR:		conf/156427 [1]
Submitted by:	Eugene Grosbein <eugen@grosbein.pp.ru> [1]