Fix standalone compilation of the tblend filter.

libavfilter/Makefile

@@ -191,7 +191,7 @@ OBJS-$(CONFIG_STEREO3D_FILTER)               += vf_stereo3d.o
 OBJS-$(CONFIG_SUBTITLES_FILTER)              += vf_subtitles.o
 OBJS-$(CONFIG_SUPER2XSAI_FILTER)             += vf_super2xsai.o
 OBJS-$(CONFIG_SWAPUV_FILTER)                 += vf_swapuv.o
-OBJS-$(CONFIG_TBLEND_FILTER)                 += vf_blend.o
+OBJS-$(CONFIG_TBLEND_FILTER)                 += vf_blend.o dualinput.o framesync.o
 OBJS-$(CONFIG_TELECINE_FILTER)               += vf_telecine.o
 OBJS-$(CONFIG_THUMBNAIL_FILTER)              += vf_thumbnail.o
 OBJS-$(CONFIG_TILE_FILTER)                   += vf_tile.o