vf_settb: rename the file as f_settb.

libavfilter/Makefile

@@ -53,7 +53,7 @@ OBJS-$(CONFIG_AMIX_FILTER)                   += af_amix.o
 OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_ARESAMPLE_FILTER)              += af_aresample.o
 OBJS-$(CONFIG_ASETNSAMPLES_FILTER)           += af_asetnsamples.o
-OBJS-$(CONFIG_ASETTB_FILTER)                 += vf_settb.o
+OBJS-$(CONFIG_ASETTB_FILTER)                 += f_settb.o
 OBJS-$(CONFIG_ASHOWINFO_FILTER)              += af_ashowinfo.o
 OBJS-$(CONFIG_ASPLIT_FILTER)                 += split.o
 OBJS-$(CONFIG_ASTREAMSYNC_FILTER)            += af_astreamsync.o
@@ -116,7 +116,7 @@ OBJS-$(CONFIG_SETDAR_FILTER)                 += vf_aspect.o
 OBJS-$(CONFIG_SETFIELD_FILTER)               += vf_setfield.o
 OBJS-$(CONFIG_SETPTS_FILTER)                 += vf_setpts.o
 OBJS-$(CONFIG_SETSAR_FILTER)                 += vf_aspect.o
-OBJS-$(CONFIG_SETTB_FILTER)                  += vf_settb.o
+OBJS-$(CONFIG_SETTB_FILTER)                  += f_settb.o
 OBJS-$(CONFIG_SHOWINFO_FILTER)               += vf_showinfo.o
 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
 OBJS-$(CONFIG_SPLIT_FILTER)                  += split.o