fate: add curves filter test.

tests/fate/filter.mak

@@ -48,6 +48,9 @@ FATE_HQDN3D += fate-filter-hqdn3d
 fate-filter-hqdn3d: CMD = framecrc -idct simple -i $(SAMPLES)/smjpeg/scenwin.mjpg -vf perms=random,hqdn3d -an
 FATE_FILTER-$(call ALLYES, SMJPEG_DEMUXER MJPEG_DECODER PERMS_FILTER HQDN3D_FILTER) += $(FATE_HQDN3D)
 
+fate-filter-curves: CMD = framecrc -i $(SAMPLES)/utvideo/utvideo_rgb_median.avi -vf "perms=random,curves=r=0/0.11@.42/.51@1/0.95:g=0.50/0.48:b=0/0.22@.49/.44@1/0.8"
+FATE_FILTER-$(call ALLYES, UTVIDEO_DECODER AVI_DEMUXER PERMS_FILTER CURVES_FILTER) += fate-filter-curves
+
 FATE_GRADFUN += fate-filter-gradfun
 fate-filter-gradfun: CMD = framecrc -i $(SAMPLES)/vmd/12.vmd -vf "sws_flags=+accurate_rnd+bitexact;format=gray,perms=random,gradfun=10:8" -an -frames:v 20
 FATE_FILTER-$(call ALLYES, VMD_DEMUXER VMDVIDEO_DECODER FORMAT_FILTER PERMS_FILTER GRADFUN_FILTER) += $(FATE_GRADFUN)

tests/ref/fate/filter-curves

@@ -0,0 +1,6 @@
+#tb 0: 1001/30000
+0,          0,          0,        1,   921600, 0xcf426780
+0,          1,          1,        1,   921600, 0x7642892d
+0,          2,          2,        1,   921600, 0x13c1ab7e
+0,          3,          3,        1,   921600, 0x3eca04bf
+0,          4,          4,        1,   921600, 0x61539162