BUILD: Not having /sbin/service is not fatal If the target platform does not have the service executable, we must not fail the build, but proceed, just disabling the functionality in sssctl. Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

BUILD: Only search for service in /sbin and /usr/sbin The shell is executed for invocation of the service binary. Therefore it is better to search the binary only in safe paths. Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

BUILD: Detect the path of the "service" executable Reviewed-by: Pavel Březina <pbrezina@redhat.com>