libavfilter/Makefile: unbreak make alltools

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/Makefile

@@ -238,8 +238,10 @@ OBJS-$(CONFIG_MOVIE_FILTER)                  += src_movie.o
 SKIPHEADERS-$(CONFIG_LIBVIDSTAB)             += vidstabutils.h
 SKIPHEADERS-$(CONFIG_OPENCL)                 += opencl_internal.h deshake_opencl_kernel.h unsharp_opencl_kernel.h
 
-TOOLS     = graph2dot zmqsend
+TOOLS     = graph2dot
 TESTPROGS = drawutils filtfmts formats
 
+TOOLS-$(CONFIG_LIBZMQ) += zmqsend
+
 clean::
 	$(RM) $(CLEANSUFFIXES:%=libavfilter/libmpcodecs/%)