[packages] netatalk: disable dtrace

fix Fedora 20 build error:
In file included from ../../include/atalk/globals.h:23:0,
                 from ../../include/atalk/unix.h:26,
                 from ad_conv.c:35:
../../include/atalk/afp_dtrace.h:9:21: fatal error: sys/sdt.h: No such file or directory

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>