rtapi_app.h/userthreads: dont include userpci/module.h if USERMODE_PCI undefined
rtapi_app.h/userthreads: dont include userpci/module.h if USERMODE_PCI undefined

this happens if libudev-dev is not installed during configure

on the bb this needs ./configure --with-posix --with-xenomai --with-platform-beaglebone
to trigger missing includes in tests/symbols.0 and tests/symbols.1

strahlex/machinekit,ArcEye/machinekit-testing,EqAfrica/machinekit,ArcEye/MK-Qt5,kinsamanka/machinekit,Cid427/machinekit,araisrobo/machinekit,EqAfrica/machinekit,unseenlaser/machinekit,araisrobo/machinekit,EqAfrica/machinekit,EqAfrica/machinekit,araisrobo/machinekit,EqAfrica/machinekit,strahlex/machinekit,strahlex/machinekit,mhaberler/machinekit,bobvanderlinden/machinekit,unseenlaser/machinekit,RunningLight/machinekit,Cid427/machinekit,unseenlaser/machinekit,ArcEye/MK-Qt5,RunningLight/machinekit,bobvanderlinden/machinekit,Cid427/machinekit,kinsamanka/machinekit,kinsamanka/machinekit,Cid427/machinekit,mhaberler/machinekit,mhaberler/machinekit,bobvanderlinden/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,RunningLight/machinekit,ArcEye/machinekit-testing,mhaberler/machinekit,strahlex/machinekit,ArcEye/machinekit-testing,Cid427/machinekit,strahlex/machinekit,strahlex/machinekit,EqAfrica/machinekit,bobvanderlinden/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,unseenlaser/machinekit,araisrobo/machinekit,mhaberler/machinekit,ArcEye/machinekit-testing,bobvanderlinden/machinekit,mhaberler/machinekit,araisrobo/machinekit,mhaberler/machinekit,EqAfrica/machinekit,RunningLight/machinekit,ArcEye/MK-Qt5,bobvanderlinden/machinekit,RunningLight/machinekit,ArcEye/machinekit-testing,kinsamanka/machinekit,araisrobo/machinekit,RunningLight/machinekit,ArcEye/machinekit-testing,unseenlaser/machinekit,ArcEye/machinekit-testing,araisrobo/machinekit,kinsamanka/machinekit,unseenlaser/machinekit,mhaberler/machinekit,kinsamanka/machinekit,araisrobo/machinekit,araisrobo/machinekit,kinsamanka/machinekit,ArcEye/MK-Qt5,ArcEye/MK-Qt5,unseenlaser/machinekit,kinsamanka/machinekit,unseenlaser/machinekit,bobvanderlinden/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,strahlex/machinekit,RunningLight/machinekit,ArcEye/machinekit-testing,bobvanderlinden/machinekit,RunningLight/machinekit,EqAfrica/machinekit