os_freebsd: version detection fixed

git-svn-id: https://smartmontools.svn.sourceforge.net/svnroot/smartmontools/trunk@2931 4ea69e1a-61f1-4043-bf83-b5c94c648137

smartmontools/os_freebsd.cpp

@@ -635,7 +635,7 @@ int freebsd_ata_device::do_cmd(struct freebsd_dev_channel* con, struct ata_ioc_r
   return ioctl(con->device, IOCATAREQUEST, request);
 }
 
-#if __FreeBSD_version > 800100
+#if FREEBSDVER > 800100
 class freebsd_atacam_device : public freebsd_ata_device
 {
 public: