avfilter/Makefile: move anullsrc and nullsink to correct place

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/Makefile

@@ -113,11 +113,11 @@ OBJS-$(CONFIG_VOLUMEDETECT_FILTER)           += af_volumedetect.o
 
 OBJS-$(CONFIG_AEVALSRC_FILTER)               += aeval.o
 OBJS-$(CONFIG_ANOISESRC_FILTER)              += asrc_anoisesrc.o
+OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
 OBJS-$(CONFIG_FLITE_FILTER)                  += asrc_flite.o
 OBJS-$(CONFIG_SINE_FILTER)                   += asrc_sine.o
 
 OBJS-$(CONFIG_ANULLSINK_FILTER)              += asink_anullsink.o
-OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
 
 # video filters
 OBJS-$(CONFIG_ALPHAEXTRACT_FILTER)           += vf_extractplanes.o
@@ -306,7 +306,6 @@ OBJS-$(CONFIG_ZSCALE_FILTER)                 += vf_zscale.o
 OBJS-$(CONFIG_ALLRGB_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_ALLYUV_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_CELLAUTO_FILTER)               += vsrc_cellauto.o
-OBJS-$(CONFIG_NULLSINK_FILTER)               += vsink_nullsink.o
 OBJS-$(CONFIG_COLOR_FILTER)                  += vsrc_testsrc.o
 OBJS-$(CONFIG_COREIMAGESRC_FILTER)           += vf_coreimage.o
 OBJS-$(CONFIG_FREI0R_SRC_FILTER)             += vf_frei0r.o
@@ -322,6 +321,8 @@ OBJS-$(CONFIG_TESTSRC_FILTER)                += vsrc_testsrc.o
 OBJS-$(CONFIG_TESTSRC2_FILTER)               += vsrc_testsrc.o
 OBJS-$(CONFIG_YUVTESTSRC_FILTER)             += vsrc_testsrc.o
 
+OBJS-$(CONFIG_NULLSINK_FILTER)               += vsink_nullsink.o
+
 # multimedia filters
 OBJS-$(CONFIG_ADRAWGRAPH_FILTER)             += f_drawgraph.o
 OBJS-$(CONFIG_AHISTOGRAM_FILTER)             += avf_ahistogram.o